Compositions and methods for reducing tactile dysfunction, anxiety, and social impairment

ABSTRACT

The present invention provides novel peripherally-restricted benzodiazepines with reduced blood brain barrier permeability and methods of use thereof for reducing tactile dysfunction, social impairment, and anxiety in a subject diagnosed with Autism Spectrum Disorder, Rett syndrome, Phelan McDermid syndrome, or Fragile X syndrome.

RELATED APPLICATIONS

This application is a national stage filing under 35 U.S.C. § 371 of International PCT Application PCT/US2020/024564, filed Mar. 25, 2020, which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application, U.S. Ser. No. 62/823,419, filed on Mar. 25, 2019, each of which is incorporated herein by reference.

FEDERALLY SPONSORED RESEARCH

This invention was made with Government support under NA101057 and NS097344 awarded by the National Institutes of Health. The Government has certain rights in the invention.

BACKGROUND OF THE INVENTION

Autism spectrum disorder (ASD) is a highly prevalent class of neurodevelopmental disorders characterized by impairments in social communication and interactions, as well as restricted and repetitive behaviors. Rates of ASD diagnoses are increasing, and the CDC identifies one in every 59 children in the United States as having ASD. In the United States alone, it is estimated that the ASD-related healthcare costs exceed 230 billion dollars per year, or 1.4 million per individual with ASD over their lifetime. A majority of ASD patients (60.9%) report altered tactile sensitivity in both glabrous (smooth) and hairy skin, and altered sensitivity to vibration and thermal pain. As with idiopathic or non-syndromic ASD, pervasive developmental disorders that cause syndromic forms of ASD are also associated with disrupted somatosensation. For example, abnormalities in tactile perception are observed in patients with Phelan McDermid Syndrome (PMS) and Fragile X syndrome, which are both highly associated with ASD and are caused by mutations in Shank3 and Fmr1, respectively Similarly, tactile hypersensitivity is common in patients with Rett syndrome (RTT), which is caused by mutations in the X-linked methyl-CpG-binding protein 2 (Mecp2) gene. There is an inverse correlation between the presence of ASD traits in human subjects and their neural responses to C-low-threshold mechanoreceptor (LTMR)-targeted affective touch. Currently, there are no FDA-approved treatments for ASD. Thus, a critical need exists for novel therapeutic approaches to treat ASD and related disorders such as Rett syndrome, Phelan McDermid Syndrome, and Fragile X syndrome.

SUMMARY OF THE INVENTION

In one aspect, this disclosure provides compounds having the structure of Formula (I):

or pharmaceutically acceptable salts thereof, wherein:

R^(A) is R^(E), hydrogen, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —OR^(D1), —N(R^(D1a))₂, or —SR^(D1), wherein R^(D1) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom;

R^(B) is R^(E), hydrogen, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group;

each instance of R^(C) and R^(D) is, independently, R^(E), hydrogen, halogen, nitro, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —OR^(D1a), —N(R^(D1))₂, or —SR^(D1a), wherein R^(D1a) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom;

X is O, NR^(F), or CHR^(F);

p is 1, 2, 3, or 4;

n is 1, 2, 3, 4, or 5;

R^(E) is a moiety that restricts the compound of Formula (I) to the peripheral nervous system, provided that the compound of Formula (I) comprises at least one R^(E); and

R^(F) is a nitrogen radical that combines with R^(B) to form a fused 5-membered heterocyclyl or heteroaryl ring.

Formula (I) comprises at least one (e.g., 1, 2, 3, or 4) instance of R^(E). In a particular embodiment, Formula (I) comprises one instance of R^(E). In certain embodiments, R^(E) is optionally substituted C₁₋₅₀ heteroaliphatic, —OR^(E1), —N(R^(E1))₂, —NO₂, —CN, —SR^(E1), —CH₂OR^(E1), —CH₂N(R^(E1))₂, —CH₂SR^(E1), —NR^(E1)C(═O)R^(E1), —C(═O)N(R^(E1))₂, —SC(═O)R^(E1), —C(═O)SR^(E1), —OC(═O)R^(E1), —C(═O)OR^(E1), —NR^(E)C(═S)R^(E1), —C(═S)NR^(E1), trans-CR^(E1)═CR^(E1), cis-CR^(E1)═CR^(E1), —C≡C—R^(E1), —S(═O)R^(E1), —S(═O)OR^(E1), —OS(═O)R^(E1), —S(═O)N(R^(E1))₂, —NR^(E1)S(═O)R^(E1), —S(═O)₂R^(E1), —S(═O)₂OR^(E1), —OS(═O)₂R^(E1), —S(═O)₂N(R^(E1))₂R^(E1), or is of the formula:

wherein

R^(E1) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom.

In certain embodiments, R^(E) is of the formula:

In some embodiments, Formula (I) has the structure of Formula (II):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (III):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (IV):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (V):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IIa):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IIb):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IIc):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IId):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (VI):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (VII):

or a pharmaceutically acceptable salt thereof.

In some embodiments, a compound of Formulae (I) or (II) has a structure selected from:

and pharmaceutically acceptable salts thereof.

In some embodiments, Formula (III) has the structure of Formula (IIIa):

or a pharmaceutically acceptable salt thereof.

In some embodiment Formula (III) has the structure of Formula (IIIb):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (III) has the structure of Formula (IIIc):

or a pharmaceutically acceptable salt thereof.

In some embodiments, the compounds of formula (III) have the structure of Formula (IIId):

or pharmaceutically acceptable salts thereof.

In some embodiments, the compounds have the structure of:

or a pharmaceutically acceptable salt thereof.

In another aspect, the invention provides a pharmaceutical composition comprising a compound or pharmaceutically acceptable salt as described herein (e.g., a compound of Formula (I), (II), (III), (IV), (V), (VI), or (VII), or a pharmaceutically acceptable salt thereof) and a pharmaceutically acceptable excipient.

In another aspect, the invention provides a method of reducing tactile dysfunction in a human subject diagnosed with Autism Spectrum Disorder (ASD), Rett Syndrome (RTT), Phelan McDermid syndrome (PMS), or Fragile X Syndrome, by administering to the subject a compound or pharmaceutically acceptable salt as described herein (e.g., a compound of Formula (I), (II), (III), (IV), (V), (VI), or (VII), or a pharmaceutically acceptable salt thereof), or a pharmaceutical composition thereof, in an amount and for a duration sufficient to reduce the tactile dysfunction.

In another aspect, the invention provides a method of reducing anxiety or social impairment in a human subject diagnosed with ASD, RTT, PMS, or Fragile X Syndrome by administering to the subject a compound or pharmaceutically acceptable salt as described herein (e.g., a compound of Formula (I), (II), (III), (IV), (V), (VI), or (VII), or a pharmaceutically acceptable salt thereof), or a pharmaceutical composition thereof, in an amount and for a duration sufficient to reduce the anxiety or social impairment.

Definitions

As used herein, the terms “Autism Spectrum Disorder” or “ASD” refer to a heterogeneous group of neurodevelopmental disorders as classified in the fifth revision of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders 5^(th) edition (DSM-5). The DSM-5 redefined the autism spectrum to encompass the prior (DSM-IV-TR) diagnosis of autism, Asperger syndrome, pervasive developmental disorder not otherwise specified, childhood disintegrative disorder, and Rett syndrome. The autism spectrum disorders are characterized by social deficits and communication difficulties, stereotyped or repetitive behaviors and interests, and in some cases, cognitive delays. For example, an ASD is defined in the DSM-5 as exhibiting (i) deficits in social communication and interaction not caused by general developmental delays (must exhibit three criteria including deficits in social-emotional reciprocity, deficits in nonverbal communication, and deficits in creating and maintaining relationships appropriate to developmental level), (ii) demonstration of restricted and repetitive patterns of behavior, interest or activities (must exhibit two of the following four criteria: repetitive speech, repetitive motor movements or repetitive use of objects, adherence to routines, ritualized patterns of verbal or nonverbal, or strong resistance to change, fixated interests that are abnormally intense of focus, and over or under reactivity to sensory input or abnormal interest in sensory aspects of environment), (iii) symptoms must be present in early childhood, and (iv) symptoms collectively limit and hinder everyday functioning. The term “ASD” is also contemplated herein to include Dravet's syndrome and autistic-like behavior in non-human animals.

As used herein, the terms “Rett syndrome” or “RTT” refer to an X-linked disorder that affects approximately one in ten-thousand girls. Patients go through four stages: Stage I) Following a period of apparently normal development from birth, the child begins to display social and communication deficits, similar to those seen in other autism spectrum disorders, between six and eighteen months of age. The child shows delays in their developmental milestones, particularly for motor ability, such as sitting and crawling. Stage II) Beginning between one and four years of age, the child goes through a period of regression in which they lose speech and motor abilities, developing stereotypical midline hand movements and gait impairments. Breathing irregularities, including apnea and hyperventilation also develop during this stage. Autistic symptoms are still prevalent at this stage. Stage III) Between age two and ten, the period of regression ends and symptoms plateau. Social and communication skills may show small improvements during this plateau period, which may last for most of the patients' lives. Stage IV) Motor ability and muscle deterioration continues. Many girls develop severe scoliosis and lose the ability to walk.

As used herein, the terms “Phelan McDermid syndrome” or “PMS” refer to rare genetic condition caused by a deletion or other structural change of the terminal end of chromosome 22 in the 22q13 region or a disease-causing mutation of the Shank3 gene. Although the range and severity of symptoms may vary, PMS is generally thought to be characterized by neonatal hypotonia (low muscle tone in the newborn), normal growth, absent to severely delayed speech, moderate to profound developmental delay, and minor dysmorphic provides. People who have PMS often show symptoms in very early childhood, sometimes at birth and within the first six months of life.

As used herein, the term “Fragile X syndrome” refers to an X chromosome-linked condition that is characterized by a visible constriction near the end of the X chromosome, at locus q27.3 that causes intellectual disability, behavioral and learning challenges and various physical characteristics Fragile X syndrome is the most common inherited form of mental retardation and developmental disability. Males with Fragile X syndrome usually have mental retardation and often exhibit characteristic physical provides and behavior. Fragile X syndrome is characterized by behavior similar to autism and attention deficit disorder, obsessive-compulsive tendencies, hyperactivity, slow development of motor skills and anxiety fear disorder. When these disabilities are severe and occur simultaneously, the condition is sometimes described as autism, and may be associated with any degree of intelligence. Other characteristics are a likable, happy, friendly personality with a limited number of autistic-like provides such as hand-flapping, finding direct eye contact unpleasant, and some speech and language problems. Physical provides may include large ears, long face, soft skin and large testicles (called “macroorchidism”) in post-pubertal males. Connective tissue problems may include ear infections, flat feet, high arched palate, double-jointed fingers and hyper-flexible joints.

As used herein, the term “tactile dysfunction” refers to exhibiting symptoms such as withdrawing when being touched, refusing to eat certain “textured” foods and/or to wear certain types of clothing, complaining about having hair or face washed, avoiding getting hands dirty (e.g., glue, sand, mud, finger-paint), and using finger tips rather than whole hands to manipulate objects. Tactile dysfunction may lead to a misperception of touch and/or pain (hyper- or hyposensitive) and may lead to self-imposed isolation, general irritability, distractibility, and hyperactivity.

As used herein, the term “anxiety” refers to emotions characterized by feelings of tension, worried thoughts and physical changes like increased blood pressure. Anxiety can be characterized by having recurring intrusive thoughts or concerns, avoiding certain situations (e.g., social situations) out of worry, and physical symptoms such as sweating, trembling, dizziness, or a rapid heartbeat.

As used herein, the term “social impairment” refers to a distinct dissociation from and lack of involvement in relations with other people. It can occur with various mental and developmental disorders, such as autism. Social impairment may occur when an individual acts in a less positive way or performs worse when they are around others as compared to when alone. Nonverbal behaviors associated with social impairment can include deficits in eye contact, facial expression, and gestures that are used to help regulate social interaction. Often there is a failure to develop age-appropriate friendships. Social impairment can also include a lack of spontaneous seeking to share achievements or interests with other individuals. A person with social impairment may exhibit a deficit in social reciprocity with individuals, decreased awareness of others, lack of empathy, and lack of awareness of the needs of others.

As used herein, the terms “blood brain barrier” and “BBB” refer to a transvascular permeability barrier that tightly controls entry of substances into the brain. The capillaries that perfuse the brain are lined with special endothelial cells that lack fenestrations and are sealed by endothelial tight junctions. The tight endothelium provides a physical barrier that together with metabolic barriers forms the basis of the BBB.

As used herein, the term “reduced permeability” refers to peripherally acting compositions of the compounds described herein that have decreased (e.g., by 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%) ability to cross the blood brain barrier.

As used herein, A “permeability reducing group” is any substituent added to a compound to reduce (e.g., by 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%) the ability of a compound to cross the blood brain barrier (e.g. by passive diffusion or active transport), as compared to the compound lacking the permeability reducing group.

As used herein, the term “reducing” refers to decreasing (e.g., by 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 97%, 99%, or about 100%) the side effects or symptoms (e.g., tactile sensitivity, social impairment, or anxiety) of patients diagnosed with ASD, RTT, PMS, or Fragile X syndrome.

As used herein, the terms “treatment” or “treating” refer to reducing, decreasing, decreasing the risk of progression, or decreasing the side effects of (e.g., by 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 97%, 99%, or about 100%) a particular disease or condition (e.g., tactile dysfunction, anxiety, and social impairment, e.g., ASD, RTT, PMS, and Fragile X syndrome). Reducing, decreasing, decreasing the risk of progression, or decreasing the side effects of are relative to a subject who did not receive treatment, e.g., a control, a baseline, or a known control level or measurement.

As used herein, the terms “effective amount” or “therapeutically effective amount” refers to an amount of a compound of the invention sufficient to produce a desired result, for example, reducing (e.g., by 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%) tactile dysfunction, social impairment, or anxiety in a subject upon administration of a composition containing a compound described herein. The increase or reduction related to administration of an effective amount of a compound may be calculated relative to levels or symptoms, as applicable, in a subject that has not been administered a compound of the invention or relative to the subject prior to administration of a compound of the invention. The increase or reduction may also be calculated relative to a control or baseline average.

As used herein, the term “subject,” refers to any animal (e.g., a mammal, e.g., a human). A subject to be treated according to the methods described herein may be one who has been diagnosed with a developmental disorder (e.g., ASD, RTT, PMS, and Fragile X syndrome) as having such a condition or one at risk of developing the condition. Diagnosis may be performed by any method or technique known in the art. One skilled in the art will understand that a subject to be treated according to the present invention may have been subjected to standard tests or may have been identified, without examination, as one at high risk due to the presence of one or more risk factors.

As used herein, the term “pharmaceutical composition,” refers to a composition containing a compound described herein formulated with a pharmaceutically acceptable excipient, and manufactured or sold with the approval of a governmental regulatory agency as part of a therapeutic regimen for the treatment of disease in a mammal. Pharmaceutical compositions can be formulated, for example, for oral administration in unit dosage form (e.g., a tablet, capsule, caplet, gelcap, or syrup); for topical administration (e.g., as a cream, gel, lotion, or ointment); for intravenous administration (e.g., as a sterile solution free of particulate emboli and in a solvent system suitable for intravenous use); for intrathecal administration (e.g., as a sterile preservative-free composition in a solvent system suitable for intrathecal use); or in any other formulation described herein.

As used herein, the terms “pharmaceutically acceptable excipient” or “pharmaceutically acceptable carrier,” refer to any ingredient in a pharmaceutical composition other than compounds described herein (e.g., a vehicle capable of suspending or dissolving the active agent) and having the properties of being nontoxic and non-inflammatory in a patient. Excipients may include, for example: antiadherents, antioxidants, binders, coatings, compression aids, disintegrants, dyes (colors), emollients, emulsifiers, fillers (diluents), film formers or coatings, flavors, fragrances, glidants (flow enhancers), lubricants, preservatives, printing inks, sorbents, suspensing or dispersing agents, sweeteners, or waters of hydration. Exemplary excipients include, but are not limited to: butylated hydroxytoluene, calcium carbonate, calcium phosphate (dibasic), calcium stearate, croscarmellose, crosslinked polyvinyl pyrrolidone, citric acid, crospovidone, cysteine, ethylcellulose, gelatin, hydroxypropyl cellulose, hydroxypropyl methylcellulose, lactose, magnesium stearate, maltitol, mannitol, methionine, methylcellulose, methyl paraben, microcrystalline cellulose, polyethylene glycol, polyvinyl pyrrolidone, povidone, pregelatinized starch, propyl paraben, retinyl palmitate, shellac, silicon dioxide, sodium carboxymethyl cellulose, sodium citrate, sodium starch glycolate, sorbitol, starch (corn), stearic acid, stearic acid, sucrose, talc, titanium dioxide, vitamin A, vitamin E, vitamin C, and xylitol.

As used herein, the term “pharmaceutically acceptable salt,” refers to those salts which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of humans and animals without undue toxicity, irritation, allergic response and the like and are commensurate with a reasonable benefit/risk ratio. Pharmaceutically acceptable salts are well known in the art. For example, pharmaceutically acceptable salts are described in: Berge et al., J. Pharmaceutical Sciences 66:1-19, 1977 and in Pharmaceutical Salts: Properties, Selection, and Use, (Eds. P. H. Stahl and C. G. Wermuth), Wiley-VCH, 2008. The salts can be prepared in situ during the final isolation and purification of the compounds described herein by reacting the free base group with a suitable organic acid. Representative acid addition salts include acetate, adipate, alginate, ascorbate, aspartate, benzenesulfonate, benzoate, bisulfate, borate, butyrate, camphorate, camphorsulfonate, citrate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, fumarate, glucoheptonate, glycerophosphate, hemisulfate, heptonate, hexanoate, hydrobromide, hydrochloride, hydroiodide, 2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, lauryl sulfate, malate, maleate, malonate, methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate, pivalate, propionate, stearate, succinate, sulfate, tartrate, thiocyanate, toluenesulfonate, undecanoate, valerate salts, and the like.

Representative alkali or alkaline earth metal salts include sodium, lithium, potassium, calcium, magnesium, and the like, as well as nontoxic ammonium, quaternary ammonium, and amine cations, including, but not limited to ammonium, tetramethylammonium, tetraethylammonium, methylamine, dimethylamine, trimethylamine, triethylamine, ethylamine, and the like.

The term “Log P” is the partition coefficient reflecting the relative solubility of a drug in octanol versus water. The higher the value, the lower the water solubility. Generally a reduction in the Log P is associated with reduced permeability across the blood brain barrier. Log P can be predicted from the structure of a compound described herein using standard physiochemical prediction software.

The term “polar surface area (PSA)” refers to the polar surface area of a molecule and is a reflection of the polarity of the molecule. Generally, higher PSA is associated with reduced permeability across the blood brain barrier. PSA can be predicted from the structure of a compound described herein using standard physiochemical prediction software.

The term “freely rotatable bonds (FRBs)” refer to the number of freely rotatable bonds a compound has. A greater number of freely rotatable bonds generally correlates with lower blood brain permeability. FRBs can be determined from the structure of a compound described herein using standard physiochemical prediction software.

The term “acyl,” as used herein, represents a hydrogen or an alkyl group, as defined herein that is attached to a parent molecular group through a carbonyl group, as defined herein, and is exemplified by formyl (i.e., a carboxyaldehyde group), acetyl, trifluoroacetyl, propionyl, and butanoyl. Exemplary unsubstituted acyl groups include from 1 to 6, from 1 to 11, or from 1 to 21 carbons.

The term “alkyl,” as used herein, refers to a branched or straight-chain monovalent saturated aliphatic hydrocarbon radical of 1 to 20 carbon atoms (e.g., 1 to 16 carbon atoms, 1 to 10 carbon atoms, or 1 to 6 carbon atoms). An alkylene is a divalent alkyl group.

The term “heteroalkyl,” as used herein, refers to an alkyl group, as defined herein, in which one or more of the constituent carbon atoms have been replaced by nitrogen, oxygen, or sulfur. In some embodiments, the heteroalkyl group can be further substituted with 1, 2, 3, or 4 substituent groups as described herein for alkyl groups. Examples of heteroalkyl groups are an “alkoxy” which, as used herein, refers to alkyl-O— (e.g., methoxy and ethoxy). A heteroalkylene is a divalent heteroalkyl group. Heteroalkyl groups also include alkylamino groups.

The term “alkylamino,” as used herein, refers to a heteroalkyl group, as defined herein, in which one or more of the constituent carbon atoms have been replaced by nitrogen. In some embodiments, the heteroalkyl group can be further substituted with 1, 2, 3, or 4 substituent groups as described herein for alkyl groups. Examples of alkylamino groups are methylamino and ethylamino.

The term “amino,” as used herein, represents —N(R^(N1))₂, wherein each R^(N1) is, independently, H, OH, NO₂, N(R^(N2))₂, SO₂OR^(N2), SO₂R^(N2), SOR^(N2), an N-protecting group, alkyl, alkoxy, aryl, arylalkyl, cycloalkyl, acyl (e.g., acetyl, trifluoroacetyl, or others described herein), wherein each of these recited R^(N1) groups can be optionally substituted; or two R^(N1) combine to form an alkylene or heteroalkylene, and wherein each R^(N2) is, independently, H, alkyl, or aryl. The amino groups of the invention can be an unsubstituted amino (i.e., —NH₂) or a substituted amino (i.e., —N(R^(N1))₂).

The term “aryl,” as used herein, represents a mono-, bicyclic, or multicyclic carbocyclic ring system having one or two aromatic rings and is exemplified by phenyl, naphthyl, 1,2-dihydronaphthyl, 1,2,3,4-tetrahydronaphthyl, anthracenyl, phenanthrenyl, fluorenyl, indanyl, indenyl, and the like, and may be optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from the group consisting of: (1) C₁-C₇ acyl (e.g., carboxyaldehyde); (2) C₁-C₂₀ alkyl (e.g., C₁-C₆ alkyl, C₁-C₆ alkoxy-C₁-C₆ alkyl, C₁-C₆ alkylsulfinyl-C₁-C₆ alkyl, amino-C₁-C₆ alkyl, azido-C₁-C₆ alkyl, (carboxyaldehyde)-C₁-C₆ alkyl, halo-C₁-C₆ alkyl (e.g., perfluoroalkyl), optionally substituted hydroxyl-C₁-C₆ alkyl, nitro-C₁-C₆ alkyl, or C₁-C₆ thioalkoxy-C₁-C₆ alkyl); (3) C₁-C₂₀ alkoxy (e.g., C₁-C₆ alkoxy, such as perfluoroalkoxy); (4) C₁-C₆ alkylsulfinyl; (5) C₆-C₁₀ aryl; (6) amino; (7) C₁-C₆ alk-C₆-C₁₀ aryl; (8) azido; (9) C₃₋₈ cycloalkyl; (10) C₁-C₆ alk-C₃₋₈ cycloalkyl; (11) halo; (12) C₁-C₁₂ heterocyclyl (e.g., C₁-C₁₂ heteroaryl); (13) (C₁-C₁₂ heterocyclyl)oxy; (14) optionally substituted hydroxyl; (15) nitro; (16) C₁-C₂₀ thioalkoxy (e.g., C₁-C₆ thioalkoxy); (17) —(CH₂)_(q)CO₂R^(A), where q is an integer from zero to four, and R^(A′) is selected from the group consisting of (a) C₁-C₆ alkyl, (b) C₆-C₁₀ aryl, (c) hydrogen, and (d) C₁-C₆ alk-C₆-C₁₀ aryl; (18) —(CH₂)_(q)CONR^(B′)R^(C′), where q is an integer from zero to four and where R^(B′) and R^(C′) are independently selected from the group consisting of (a) hydrogen, (b) C₁-C₆ alkyl, (c) C₆-C₁₀ aryl, and (d) C₁-C₆ alk-C₆-C₁₀ aryl; (19) —(CH₂)_(q)SO₂R^(D′), where q is an integer from zero to four and where R^(D′) is selected from the group consisting of (a) alkyl, (b) C₆-C₁₀ aryl, and (c) alk-C₆-C₁₀ aryl; (20) —(CH₂)_(q)SO₂NR^(E′)R^(F′), where q is an integer from zero to four and where each of R^(E′) and R^(F′) is, independently, selected from the group consisting of (a) hydrogen, (b) C₁-C₆ alkyl, (c) C₆-C₁₀ aryl, and (d) C₁-C₆ alk-C₆-C₁₀ aryl; (21) optionally substituted thiol; (22) C₆-C₁₀ aryloxy; (23) C₃₋₈ cycloalkoxy; (24) C₆-C₁₀ aryl-C₁-C₆ alkoxy; (25) C₁-C₆ alk-C₁-C₁₂ heterocyclyl (e.g., C₁-C₆ alk-C₁-C₁₂ heteroaryl); (26) C₂-C₂₀ alkenyl; (27) C₂-C₂₀ alkynyl; and (28) nitrile groups (e.g., cyano). In some embodiments, each of these groups can be further substituted as described herein. For example, the alkylene group of a C₁-alkaryl or a C₁-alkheterocyclyl can be further substituted with an oxo group to afford the respective aryloyl and (heterocyclyl)oyl substituent group.

The term “cycloalkyl,” as used herein, represents a monovalent saturated or unsaturated non-aromatic cyclic hydrocarbon group from three to eight carbons, unless otherwise specified, and is exemplified by cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, bicycle heptyl, and the like. When the cycloalkyl group includes one carbon-carbon double bond, the cycloalkyl group can be referred to as a “cycloalkenyl” group. Exemplary cycloalkenyl groups include cyclopentenyl, cyclohexenyl, and the like. The cycloalkyl groups of this invention can be optionally substituted with: (1) C₁-C₇ acyl (e.g., carboxyaldehyde); (2) C₁-C₂₀ alkyl (e.g., C₁-C₆ alkyl, C₁-C₆ alkoxy-C₁-C₆ alkyl, C₁-C₆ alkylsulfinyl-C₁-C₆ alkyl, amino-C₁-C₆ alkyl, azido-C₁-C₆ alkyl, (carboxyaldehyde)-C₁-C₆ alkyl, halo-C₁-C₆ alkyl (e.g., perfluoroalkyl), optionally substituted hydroxyl-C₁-C₆ alkyl, nitro-C₁-C₆ alkyl, or C₁-C₆ thioalkoxy-C₁-C₆ alkyl); (3) C₁-C₂₀ alkoxy (e.g., C₁-C₆ alkoxy, such as perfluoroalkoxy); (4) C₁-C₆ alkylsulfinyl; (5) C₆-C₁₀ aryl; (6) amino; (7) C₁-C₆ alk-C₆-C₁₀ aryl; (8) azido; (9) C₃₋₈ cycloalkyl; (10) C₁-C₆ alk-C₃₋₈ cycloalkyl; (11) halo; (12) C₁-C₁₂ heterocyclyl (e.g., C₁-C₁₂ heteroaryl); (13) (C₁-C₁₂ heterocyclyl)oxy; (14) optionally substituted hydroxyl; (15) nitro; (16) C₁-C₂₀ thioalkoxy (e.g., C₁-C₆ thioalkoxy); (17) —(CH₂)_(q)CO₂R^(A′), where q is an integer from zero to four, and R^(A′) is selected from the group consisting of (a) C₁-C₆ alkyl, (b) C₆-C₁₀ aryl, (c) hydrogen, and (d) C₁-C₆ alk-C₆-C₁₀ aryl; (18) —(CH₂)_(q)CONR^(B′)R^(C′), where q is an integer from zero to four and where R^(B′) and R^(C′) are independently selected from the group consisting of (a) hydrogen, (b) C₆-C₁₀ alkyl, (c) C₆-C₁₀ aryl, and (d) C₁-C₆ alk-C₆-C₁₀ aryl; (19) —(CH₂)_(q)SO₂R^(D′), where q is an integer from zero to four and where R^(D′) is selected from the group consisting of (a) C₆-C₁₀ alkyl, (b) C₆-C₁₀ aryl, and (c) C₁-C₆ alk-C₆-C₁₀ aryl; (20) —(CH₂)_(q)SO₂NR^(E′)R^(F′), where q is an integer from zero to four and where each of R^(E′) and R^(F′) is, independently, selected from the group consisting of (a) hydrogen, (b) C₆-C₁₀ alkyl, (c) C₆-C₁₀ aryl, and (d) C₁-C₆ alk-C₆-C₁₀ aryl; (21) optionally substituted thiol; (22) C₆-C₁₀ aryloxy; (23) C₃₋₈ cycloalkoxy; (24) C₆-C₁₀ aryl-C₁-C₆ alkoxy; (25) C₁-C₆ alkyl-C₁-C₁₂ heterocyclyl (e.g., C₁-C₆ alk-C₁-C₁₂ heteroaryl); (26) oxo; (27) C₂-C₂₀ alkenyl; and (28) C₂-C₂₀ alkynyl. In some embodiments, each of these groups can be further substituted as described herein. For example, the alkylene group of a C₁-alkaryl or a C₁-alkheterocyclyl can be further substituted with an oxo group to afford the respective aryloyl and (heterocyclyl)oyl substituent group.

The term “halogen,” as used herein, refers to bromine, chlorine, iodine, or fluorine.

The term “N-protecting group,” as used herein, represents those groups intended to protect an amino group against undesirable reactions during synthetic procedures. Commonly used N-protecting groups are disclosed in Greene, “Protective Groups in Organic Synthesis,” 3^(rd) Edition (John Wiley & Sons, New York, 1999). N-protecting groups include acyl, aryloyl, or carbamyl groups such as formyl, acetyl, propionyl, pivaloyl, t-butylacetyl, 2-chloroacetyl, 2-bromoacetyl, trifluoroacetyl, trichloroacetyl, phthalyl, o-nitrophenoxyacetyl, α-chlorobutyryl, benzoyl, 4-chlorobenzoyl, 4-bromobenzoyl, 4-nitrobenzoyl, and chiral auxiliaries such as protected or unprotected D, L or D, L-amino acids such as alanine, leucine, and phenylalanine; sulfonyl-containing groups such as benzenesulfonyl, and p-toluenesulfonyl; carbamate forming groups such as benzyloxycarbonyl, p-chlorobenzyloxycarbonyl, p-methoxybenzyloxycarbonyl, p-nitrobenzyloxycarbonyl, 2-nitrobenzyloxycarbonyl, p-bromobenzyloxycarbonyl, 3,4-dimethoxybenzyloxycarbonyl, 3,5-dimethoxybenzyloxycarbonyl, 2,4-dimethoxybenzyloxycarbonyl, 4-methoxybenzyloxycarbonyl, 2-nitro-4,5-dimethoxybenzyloxycarbonyl, 3,4,5-trimethoxybenzyloxycarbonyl, 1-(p-biphenylyl)-1-methylethoxycarbonyl, α,α-dimethyl-3,5-dimethoxybenzyloxycarbonyl, benzhydryloxy carbonyl, t-butyloxycarbonyl, diisopropylmethoxycarbonyl, isopropyloxycarbonyl, ethoxycarbonyl, methoxycarbonyl, allyloxycarbonyl, 2,2,2,-trichloroethoxycarbonyl, phenoxycarbonyl, 4-nitrophenoxy carbonyl, fluorenyl-9-methoxycarbonyl, cyclopentyloxycarbonyl, adamantyloxycarbonyl, cyclohexyloxycarbonyl, and phenylthiocarbonyl, arylalkyl groups such as benzyl, triphenylmethyl, and benzyloxymethyl, and silyl groups, such as trimethylsilyl. Preferred N-protecting groups are alloc, formyl, acetyl, benzoyl, pivaloyl, t-butylacetyl, alanyl, phenylsulfonyl, benzyl, t-butyloxycarbonyl (Boc), and benzyloxycarbonyl (Cbz).

The term “O-protecting group,” as used herein, represents those groups intended to protect an oxygen containing (e.g., phenol, optionally substituted hydroxyl, or carbonyl) group against undesirable reactions during synthetic procedures. Commonly used O-protecting groups are disclosed in Greene, “Protective Groups in Organic Synthesis,” 3′ Edition (John Wiley & Sons, New York, 1999), which is incorporated herein by reference. Exemplary O-protecting groups include acyl, aryloyl, or carbamyl groups, such as formyl, acetyl, propionyl, pivaloyl, t-butylacetyl, 2-chloroacetyl, 2-bromoacetyl, trifluoroacetyl, trichloroacetyl, phthalyl, o-nitrophenoxyacetyl, α-chlorobutyryl, benzoyl, 4-chlorobenzoyl, 4-bromobenzoyl, t-butyldimethylsilyl, tri-iso-propylsilyloxymethyl, 4,4′-dimethoxytrityl, isobutyryl, phenoxyacetyl, 4-isopropylpehenoxyacetyl, dimethylformamidino, and 4-nitrobenzoyl; alkylcarbonyl groups, such as acyl, acetyl, propionyl, pivaloyl, and the like; optionally substituted arylcarbonyl groups, such as benzoyl; silyl groups, such as trimethylsilyl (TMS), tert-butyldimethylsilyl (TBDMS), tri-iso-propylsilyloxymethyl (TOM), triisopropylsilyl (TIPS), and the like; ether-forming groups with the optionally substituted hydroxyl, such methyl, methoxymethyl, tetrahydropyranyl, benzyl, p-methoxybenzyl, trityl, and the like; alkoxycarbonyls, such as methoxycarbonyl, ethoxycarbonyl, isopropoxycarbonyl, n-isopropoxycarbonyl, n-butyloxycarbonyl, isobutyloxycarbonyl, sec-butyloxycarbonyl, t-butyloxycarbonyl, 2-ethylhexyloxycarbonyl, cyclohexyloxycarbonyl, methyloxycarbonyl, and the like; alkoxyalkoxycarbonyl groups, such as methoxymethoxycarbonyl, ethoxymethoxycarbonyl, 2-methoxyethoxycarbonyl, 2-ethoxyethoxycarbonyl, 2-butoxyethoxycarbonyl, 2-methoxyethoxymethoxycarbonyl, allyloxycarbonyl, propargyloxycarbonyl, 2-butenoxycarbonyl, 3-methyl-2-butenoxycarbonyl, and the like; haloalkoxycarbonyls, such as 2-chloroethoxycarbonyl, 2-chloroethoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, and the like; optionally substituted arylalkoxycarbonyl groups, such as benzyloxycarbonyl, p-methylbenzyloxycarbonyl, p-methoxybenzyloxycarbonyl, p-nitrobenzyloxycarbonyl, 2,4-dinitrobenzyloxycarbonyl, 3,5-dimethylbenzyloxycarbonyl, p-chlorobenzyloxycarbonyl, p-bromobenzyloxy-carbonyl, fluorenylmethyloxycarbonyl, and the like; and optionally substituted aryloxycarbonyl groups, such as phenoxycarbonyl, p-nitrophenoxycarbonyl, o-nitrophenoxycarbonyl, 2,4-dinitrophenoxycarbonyl, p-methyl-phenoxycarbonyl, m-methylphenoxycarbonyl, o-bromophenoxycarbonyl, 3,5-dimethylphenoxycarbonyl, p-chlorophenoxycarbonyl, 2-chloro-4-nitrophenoxy-carbonyl, and the like); substituted alkyl, aryl, and alkaryl ethers (e.g., trityl; methylthiomethyl; methoxymethyl; benzyloxymethyl; siloxymethyl; 2,2,2,-trichloroethoxymethyl; tetrahydropyranyl; tetrahydrofuranyl; ethoxyethyl; 1-[2-(trimethylsilyl)ethoxy]ethyl; 2-trimethylsilylethyl; t-butyl ether; p-chlorophenyl, p-methoxyphenyl, p-nitrophenyl, benzyl, p-methoxybenzyl, and nitrobenzyl); silyl ethers (e.g., trimethylsilyl; triethylsilyl; triisopropylsilyl; dimethylisopropylsilyl; t-butyldimethylsilyl; t-butyldiphenylsilyl; tribenzylsilyl; triphenylsilyl; and diphenymethylsilyl); carbonates (e.g., methyl, methoxymethyl, 9-fluorenylmethyl; ethyl; 2,2,2-trichloroethyl; 2-(trimethylsilyl)ethyl; vinyl, allyl, nitrophenyl; benzyl; methoxybenzyl; 3,4-dimethoxybenzyl; and nitrobenzyl); carbonyl-protecting groups (e.g., acetal and ketal groups, such as dimethyl acetal, 1,3-dioxolane, and the like; acylal groups; and dithiane groups, such as 1,3-dithianes, 1,3-dioptionally substituted thiolane, and the like); carboxylic acid-protecting groups (e.g., ester groups, such as methyl ester, benzyl ester, t-butyl ester, orthoesters, and the like; and oxazoline groups.

The term “urea,” as used herein, refers to a carbamide with two —NR¹R² groups joined by a carbonyl. R¹ and R² can be optionally substituted C₁₋₆ alkyl, hydrogen, or deuterium.

The term “carbamate,” as used herein, refers to a chemical group of R¹—O—CO—NR²R³ wherein R¹, R², and R³ can be any chemical group, such as optionally substituted C₁₋₆ alkyl.

The term “sulfonamide,” as used herein, refers to a chemical group of —S(═O)₂—NH₂.

The alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl (e.g., cycloalkyl), aryl, heteroaryl, and heterocyclyl groups may be substituted or unsubstituted. When substituted, there will generally be 1 to 4 substituents present, unless otherwise specified.

Substituents include, for example: aryl (e.g., substituted and unsubstituted phenyl), carbocyclyl (e.g., substituted and unsubstituted cycloalkyl), halogen (e.g., fluoro), hydroxyl, heteroalkyl (e.g., substituted and unsubstituted methoxy, ethoxy, or thioalkoxy), heteroaryl, heterocyclyl, amino (e.g., NH₂ or mono- or dialkyl amino), azido, cyano, nitro, or thiol. Aryl, carbocyclyl (e.g., cycloalkyl), heteroaryl, and heterocyclyl groups may also be substituted with alkyl (unsubstituted and substituted such as arylalkyl (e.g., substituted and unsubstituted benzyl)).

Those skilled in the art will appreciate that certain compounds described herein can exist in one or more different isomeric (e.g., stereoisomers, geometric isomers, tautomers) and/or isotopic (e.g., in which one or more atoms has been substituted with a different isotope of the atom, such as hydrogen substituted for deuterium) forms. Unless otherwise indicated or clear from context, a depicted structure can be understood to represent any such isomeric or isotopic form, individually or in combination.

Compounds of the invention can have one or more asymmetric carbon atoms and can exist in the form of optically pure enantiomers, mixtures of enantiomers such as, for example, racemates, optically pure diastereoisomers, mixtures of diastereoisomers, diastereoisomeric racemates or mixtures of diastereoisomeric racemates. The optically active forms can be obtained for example by resolution of the racemates, by asymmetric synthesis or asymmetric chromatography (chromatography with a chiral adsorbents or eluant). That is, certain of the disclosed compounds may exist in various stereoisomeric forms. Stereoisomers are compounds that differ only in their spatial arrangement. Enantiomers are pairs of stereoisomers whose mirror images are not superimposable, most commonly because they contain an asymmetrically substituted carbon atom that acts as a chiral center. “Enantiomer” means one of a pair of molecules that are mirror images of each other and are not superimposable. Diastereomers are stereoisomers that are not related as mirror images, most commonly because they contain two or more asymmetrically substituted carbon atoms and represent the configuration of substituents around one or more chiral carbon atoms. Enantiomers of a compound can be prepared, for example, by separating an enantiomer from a racemate using one or more well-known techniques and methods, such as, for example, chiral chromatography and separation methods based thereon. The appropriate technique and/or method for separating an enantiomer of a compound described herein from a racemic mixture can be readily determined by those of skill in the art. “Racemate” or “racemic mixture” means a compound containing two enantiomers, wherein such mixtures exhibit no optical activity; i.e., they do not rotate the plane of polarized light. “Geometric isomer” means isomers that differ in the orientation of substituent atoms in relationship to a carbon-carbon double bond, to a cycloalkyl ring, or to a bridged bicyclic system. Atoms (other than H) on each side of a carbon-carbon double bond may be in an E (substituents are on opposite sides of the carbon-carbon double bond) or Z (substituents are oriented on the same side) configuration. “R,” “S,” “S*,” “R*,” “E,” “Z,” “cis,” and “trans,” indicate configurations relative to the core molecule. Certain of the disclosed compounds may exist in atropisomeric forms.

Atropisomers are stereoisomers resulting from hindered rotation about single bonds where the steric strain barrier to rotation is high enough to allow for the isolation of the conformers. The compounds of the invention may be prepared as individual isomers by either isomer-specific synthesis or resolved from an isomeric mixture. Conventional resolution techniques include forming the salt of a free base of each isomer of an isomeric pair using an optically active acid (followed by fractional crystallization and regeneration of the free base), forming the salt of the acid form of each isomer of an isomeric pair using an optically active amine (followed by fractional crystallization and regeneration of the free acid), forming an ester or amide of each of the isomers of an isomeric pair using an optically pure acid, amine or alcohol (followed by chromatographic separation and removal of the chiral auxiliary), or resolving an isomeric mixture of either a starting material or a final product using various well known chromatographic methods. When the stereochemistry of a disclosed compound is named or depicted by structure, the named or depicted stereoisomer is at least 60%, 70%, 80%, 90%, 99% or 99.9%) by weight relative to the other stereoisomers. When a single enantiomer is named or depicted by structure, the depicted or named enantiomer is at least 60%, 70%, 80%, 90%, 99% or 99.9% by weight optically pure. When a single diastereomer is named or depicted by structure, the depicted or named diastereomer is at least 60%, 70%, 80%, 90%, 99% or 99.9% by weight pure. Percent optical purity is the ratio of the weight of the enantiomer or over the weight of the enantiomer plus the weight of its optical isomer. Diastereomeric purity by weight is the ratio of the weight of one diastereomer or over the weight of all the diastereomers. When the stereochemistry of a disclosed compound is named or depicted by structure, the named or depicted stereoisomer is at least 60%, 70%, 80%, 90%, 99% or 99.9% by mole fraction pure relative to the other stereoisomers. When a single enantiomer is named or depicted by structure, the depicted or named enantiomer is at least 60%, 70%, 80%, 90%, 99% or 99.9% by mole fraction pure. When a single diastereomer is named or depicted by structure, the depicted or named diastereomer is at least 60%, 70%, 80%, 90%, 99% or 99.9% by mole fraction pure. Percent purity by mole fraction is the ratio of the moles of the enantiomer or over the moles of the enantiomer plus the moles of its optical isomer. Similarly, percent purity by moles fraction is the ratio of the moles of the diastereomer or over the moles of the diastereomer plus the moles of its isomer. When a disclosed compound is named or depicted by structure without indicating the stereochemistry, and the compound has at least one chiral center, it is to be understood that the name or structure encompasses either enantiomer of the compound free from the corresponding optical isomer, a racemic mixture of the compound or mixtures enriched in one enantiomer relative to its corresponding optical isomer. When a disclosed compound is named or depicted by structure without indicating the stereochemistry and has two or more chiral centers, it is to be understood that the name or structure encompasses a diastereomer free of other diastereomers, a number of diastereomers free from other diastereomeric pairs, mixtures of diastereomers, mixtures of diastereomeric pairs, mixtures of diastereomers in which one diastereomer is enriched relative to the other diastereomer(s) or mixtures of diastereomers in which one or more diastereomer is enriched relative to the other diastereomers. The invention embraces all of these forms.

In some embodiments, one or more compounds depicted herein may exist in different tautomeric forms. As will be clear from context, unless explicitly excluded, references to such compounds encompass all such tautomeric forms. In some embodiments, tautomeric forms result from the swapping of a single bond with an adjacent double bond and the concomitant migration of a proton. In certain embodiments, a tautomeric form may be a prototropic tautomer, which is an isomeric protonation states having the same empirical formula and total charge as a reference form. Examples of moieties with prototropic tautomeric forms are ketone-enol pairs, amide-imidic acid pairs, lactam-lactim pairs, amide-imidic acid pairs, enamine-imine pairs, and annular forms where a proton can occupy two or more positions of a heterocyclic system, such as, 1H- and 3H-imidazole, 1H-, 2H- and 4H-1,2,4-triazole, 1H- and 2H-isoindole, and 1H- and 2H-pyrazole. In some embodiments, tautomeric forms can be in equilibrium or sterically locked into one form by appropriate substitution.

Those skilled in the art will appreciate that, in some embodiments, isotopes of compounds described herein may be prepared and/or utilized in accordance with the present invention. “Isotopes” refers to atoms having the same atomic number but different mass numbers resulting from a different number of neutrons in the nuclei. For example, isotopes of hydrogen include tritium and deuterium. In some embodiments, an isotopic substitution (e.g., substitution of hydrogen with deuterium) may alter the physicochemical properties of the molecules, such as metabolism and/or the rate of racemization of a chiral center.

As is known in the art, many chemical entities (in particular many organic molecules and/or many small molecules) can adopt a variety of different solid forms such as, for example, amorphous forms and/or crystalline forms (e.g., polymorphs, hydrates, solvates, etc.). In some embodiments, such entities may be utilized in any form, including in any solid form. In some embodiments, such entities are utilized in a particular form, for example in a particular solid form.

In some embodiments, compounds described and/or depicted herein may be provided and/or utilized in salt form.

In certain embodiments, compounds described and/or depicted herein may be provided and/or utilized in hydrate or solvate form.

At various places in the present specification, substituents of compounds of the present disclosure are disclosed in groups or in ranges. It is specifically intended that the present disclosure include each and every individual subcombination of the members of such groups and ranges. For example, the term “C₁-C₆ alkyl” is specifically intended to individually disclose methyl, ethyl, C₃ alkyl, C₄ alkyl, C₅ alkyl, and C₆ alkyl. Furthermore, where a compound includes a plurality of positions at which substitutes are disclosed in groups or in ranges, unless otherwise indicated, the present disclosure is intended to cover individual compounds and groups of compounds (e.g., genera and subgenera) containing each and every individual subcombination of members at each position.

Herein a phrase of the form “optionally substituted X” (e.g., optionally substituted alkyl) is intended to be equivalent to “X, wherein X is optionally substituted” (e.g., “alkyl, wherein said alkyl is optionally substituted”). It is not intended to mean that the feature “X” (e.g. alkyl) per se is optional. As used herein, the term “optionally substituted X” (e.g., optionally substituted alkyl) means that X can be substituted with any substituent, e.g., any of the substituents described herein.

“Optionally substituted” refers to a group which may be substituted or unsubstituted (e.g., “substituted” or “unsubstituted” alkyl, “substituted” or “unsubstituted” alkenyl, “substituted” or “unsubstituted” alkynyl, “substituted” or “unsubstituted” heteroalkyl, “substituted” or “unsubstituted” heteroalkenyl, “substituted” or “unsubstituted” heteroalkynyl, “substituted” or “unsubstituted” carbocyclyl, “substituted” or “unsubstituted” heterocyclyl, “substituted” or “unsubstituted” aryl or “substituted” or “unsubstituted” heteroaryl group). In general, the term “substituted” means that at least one hydrogen present on a group is replaced with a permissible substituent, e.g., a substituent which upon substitution results in a stable compound, e.g., a compound which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, or other reaction. Unless otherwise indicated, a “substituted” group has a substituent at one or more substitutable positions of the group, and when more than one position in any given structure is substituted, the substituent is either the same or different at each position. The term “substituted” is contemplated to include substitution with all permissible substituents of organic compounds, and includes any of the substituents described herein that results in the formation of a stable compound. The present invention contemplates any and all such combinations in order to arrive at a stable compound. For purposes of this invention, heteroatoms such as nitrogen may have hydrogen substituents and/or any suitable substituent as described herein which satisfy the valencies of the heteroatoms and results in the formation of a stable moiety. The invention is not intended to be limited in any manner by the exemplary substituents described herein.

Exemplary carbon atom substituents include, but are not limited to, halogen, —CN, —NO₂, —N₃, —SO₂H, —SO₃H, —OH, —OR^(aa), —ON(R^(bb))₂, —N(R^(bb))₂, —N(R^(bb))₃ ⁺X⁻, —N(OR^(cc))R^(bb), —SH, —SR^(aa), —SSR^(cc), —C(═O)R^(aa), —CO₂H, —CHO, —C(OR^(cc))₂, —CO₂R^(aa), —OC(═O)R^(aa), —OCO₂R^(aa), —C(═O)N(R^(bb))₂, —OC(═O)N(R^(bb))₂, —NR^(bb)C(═O)R^(aa), —NR^(bb)CO₂R^(aa), —NR^(bb)C(═O)N(R^(bb))₂, —C(═NR^(bb))R^(aa), —C(═NR^(bb))OR^(aa), —OC(═NR^(bb))R^(aa), —OC(═NR^(bb))OR^(aa), —C(═NR^(bb))N(R^(bb))₂, —OC(═NR^(bb))N(R^(bb))₂, —NR^(bb)C(═NR^(bb))N(R^(bb))₂, —C(═O)NR^(bb)SO₂R^(aa), —NR^(bb)SO₂R^(aa), —SO₂N(R^(bb))₂, —SO₂R^(aa), —SO₂OR^(aa), —OSO₂R^(aa), —S(═O)R^(aa), —OS(═O)R^(aa), —Si(R^(aa))₃, —OSi(R^(aa))₃—C(═S)N(R^(bb))₂, —C(═O)SR^(aa), —C(═S)SR^(aa), —SC(═S)SR^(aa), —SC(═O)SR^(aa), —OC(═O)SR^(aa), —SC(═O)OR^(aa), —SC(═O)R^(aa), —P(═O)₂R^(aa), —OP(═O)₂R^(aa), —P(═O)(R^(aa))₂, —OP(═O)(R^(aa))₂, —OP(═O)(OR^(cc))₂, —P(═O)₂N(R^(bb))₂, —OP(═O)₂N(R^(bb))₂, —P(═O)(NR^(aa))₂, —OP(═O)(NR^(bb))₂, —NR^(bb)P(═O)(OR^(cc))₂, —NR^(bb)P(═O)(NR^(bb))₂, —P(R^(cc))₂, —P(R^(cc))₃, —OP(R^(cc))₂, —OP(R^(cc))₃, —B(R^(aa))₂, —B(OR^(cc))₂, —BR^(aa)(OR^(cc)), C₁₋₁₀ alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, heteroC₁₋₁₀ alkyl, heteroC₂₋₁₀ alkenyl, heteroC₂₋₁₀ alkynyl, C₃₋₁₀ carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 membered heteroaryl, wherein each alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups;

or two geminal hydrogens on a carbon atom are replaced with the group ═O, ═S, ═NN(R^(bb))₂, ═NNR^(bb)C(═O)R^(aa), ═NNR^(bb)C(═O)OR^(aa), ═NNR^(bb)S(═O)₂R^(aa), ═NR^(bb), or ═NOR^(cc);

each instance of R^(aa) is, independently, selected from C₁₋₁₀ alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, heteroC₁₋₁₀ alkyl, heteroC₂₋₁₀alkenyl, heteroC₂₋₁₀alkynyl, C₃₋₁₀ carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 membered heteroaryl, or two R^(aa) groups are joined to form a 3-14 membered heterocyclyl or 5-14 membered heteroaryl ring, wherein each alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups;

each instance of R^(bb) is, independently, selected from hydrogen, —OH, —OR^(aa), —N(R^(cc))₂, —CN, —C(═O)R^(aa), —C(═O)N(R^(cc))₂, —CO₂R^(aa), —SO₂R^(aa), —C(═NR^(cc))OR^(aa), —C(═NR^(cc))N(R^(cc))₂, —SO₂N(R^(cc))₂, —SO₂R^(cc), —SO₂OR^(cc), —SOR^(aa), —C(═S)N(R^(cc))₂, —C(═O)SR^(cc), —C(═S)SR^(cc), —P(═O)₂R^(aa), —P(═O)(R^(aa))₂, —P(═O)₂N(R^(cc))₂, —P(═O)(NR^(cc))₂, C₁₋₁₀ alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, heteroC₁₋₁₀alkyl, heteroC₂₋₁₀alkenyl, heteroC₂₋₁₀alkynyl, C₃₋₁₀ carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 membered heteroaryl, or two R^(bb) groups are joined to form a 3-14 membered heterocyclyl or 5-14 membered heteroaryl ring, wherein each alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups;

each instance of R^(cc) is, independently, selected from hydrogen, C₁₋₁₀ alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, heteroC₁₋₁₀ alkyl, heteroC₂₋₁₀ alkenyl, heteroC₂₋₁₀ alkynyl, C₃₋₁₀ carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 membered heteroaryl, or two R^(cc) groups are joined to form a 3-14 membered heterocyclyl or 5-14 membered heteroaryl ring, wherein each alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups;

each instance of R^(dd) is, independently, selected from halogen, —CN, —NO₂, —N₃, —SO₂H, —SO₃H, —OH, —OR^(ee), —ON(R^(ff))₂, —N(R^(ff))₂, —N(R^(ff))₃ ⁺X⁻, —N(OR^(ee))R^(ff), —SH, —SR^(ee), —SSR^(ee), —C(═O)R^(ee), —CO₂H, —CO₂R^(ee), —OC(═O)R^(ee), —OCO₂R^(ee), —C(═O)N(R^(ff))₂, —OC(═O)N(R^(ff))₂, —NR^(ff)C(═O)R^(ee), —NR^(ff)CO₂R^(ee), —NR^(ff)C(═O)N(R^(ff))₂, —C(═NR^(ff))OR^(ee), —OC(═NR^(ff))R^(ee), —OC(═NR^(ff))OR^(ee), —C(═NR^(ff))N(R^(ff))₂, —OC(═NR^(ff))N(R^(ff))₂, —NR^(ff)C(═NR^(ff))N(R^(ff))₂, —NR^(ff)SO₂R^(ee), —SO₂N(R^(ff))₂, —SO₂R^(ee), —SO₂OR^(ee), —OSO₂R^(ee), —S(═O)R^(ee), —Si(R^(ee))₃, —OSi(R^(ee))₃, —C(═S)N(R^(ff))₂, —C(═O)SR^(ee), —C(═S)SR^(ee), —SC(═S)SR^(ee), —P(═O)₂R^(ee), —P(═O)(R^(ee))₂, —OP(═O)(R^(ee))₂, —OP(═O)(OR^(ee))₂, C₁₋₆ alkyl, C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, heteroC₁₋₆alkyl, heteroC₂₋₆alkenyl, heteroC₂₋₆alkynyl, C₃₋₁₀ carbocyclyl, 3-10 membered heterocyclyl, C₆₋₁₀ aryl, 5-10 membered heteroaryl, wherein each alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(gg) groups, or two geminal R^(dd) substituents can be joined to form ═O or ═S;

each instance of R^(ee) is, independently, selected from C₁₋₆ alkyl, C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, heteroC₁₋₆ alkyl, heteroC₂₋₆ alkenyl, heteroC₂₋₆ alkynyl, C₃₋₁₀ carbocyclyl, C₆₋₁₀ aryl, 3-10 membered heterocyclyl, and 3-10 membered heteroaryl, wherein each alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(gg) groups;

each instance of R^(ff) is, independently, selected from hydrogen, C₁₋₆ alkyl, C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, heteroC₁₋₆alkyl, heteroC₂₋₆alkenyl, heteroC₂₋₆alkynyl, C₃₋₁₀ carbocyclyl, 3-10 membered heterocyclyl, C₆₋₁₀ aryl and 5-10 membered heteroaryl, or two R^(ff) groups are joined to form a 3-10 membered heterocyclyl or 5-10 membered heteroaryl ring, wherein each alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(gg) groups; and

each instance of R^(gg) is, independently, halogen, —CN, —NO₂, —N₃, —SO₂H, —SO₃H, —OH, —OC₁₋₆ alkyl, —ON(C₁₋₆ alkyl)₂, —N(C₁₋₆ alkyl)₂, —N(C₁₋₆ alkyl)₃ ⁺X⁻, —NH(C₁₋₆ alkyl)₂ ⁺X⁻, —NH₂(C₁₋₆ alkyl)⁺X⁻, —NH₃ ⁺X⁻, —N(OC₁₋₆ alkyl)(C₁₋₆ alkyl), —N(OH)(C₁₋₆ alkyl), —NH(OH), —SH, —SC₁₋₆ alkyl, —SS(C₁₋₆ alkyl), —C(═O)(C₁₋₆ alkyl), —CO₂H, —CO₂(C₁₋₆ alkyl), —OC(═O)(C₁₋₆ alkyl), —OCO₂(C₁₋₆ alkyl), —C(═O)NH₂, —C(═O)N(C₁₋₆ alkyl)₂, —OC(═O)NH(C₁₋₆ alkyl), —NHC(═O)(C₁₋₆ alkyl), —N(C₁₋₆ alkyl)C(═O)(C₁₋₆ alkyl), —NHCO₂(C₁₋₆ alkyl), —NHC(═O)N(C₁₋₆ alkyl)₂, —NHC(═O)NH(C₁₋₆ alkyl), —NHC(═O)NH₂, —C(═NH)O(C₁₋₆ alkyl), —OC(═NH)(C₁₋₆ alkyl), —OC(═NH)OC₁₋₆ alkyl, —C(═NH)N(C₁₋₆ alkyl)₂, —C(═NH)NH(C₁₋₆ alkyl), —C(═NH)NH₂, —OC(═NH)N(C₁₋₆ alkyl)₂, —OC(NH)NH(C₁₋₆ alkyl), —OC(NH)NH₂, —NHC(NH)N(C₁₋₆ alkyl)₂, —NHC(═NH)NH₂, —NHSO₂(C₁₋₆ alkyl), —SO₂N(C₁₋₆ alkyl)₂, —SO₂NH(C₁₋₆ alkyl), —SO₂NH₂, —SO₂C₁₋₆ alkyl, —SO₂OC₁₋₆ alkyl, —OSO₂C₁₋₆ alkyl, —SOC₁₋₆ alkyl, —Si(C₁₋₆ alkyl)₃, —OSi(C₁₋₆ alkyl)₃-C(═S)N(C₁₋₆ alkyl)₂, C(═S)NH(C₁₋₆ alkyl), C(═S)NH₂, —C(═O)S(C₁₋₆ alkyl), —C(═S)SC₁₋₆ alkyl, —SC(═S)SC₁₋₆ alkyl, —P(═O)₂(C₁₋₆ alkyl), —P(═O)(C₁₋₆ alkyl)₂, —OP(═O)(C₁₋₆ alkyl)₂, —OP(═O)(OC₁₋₆ alkyl)₂, C₁₋₆ alkyl, C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, heteroC₁₋₆alkyl, heteroC₂₋₆alkenyl, heteroC₂₋₆alkynyl, C₃₋₁₀ carbocyclyl, C₆₋₁₀ aryl, 3-10 membered heterocyclyl, 5-10 membered heteroaryl; or two geminal RN substituents can be joined to form ═O or ═S; wherein X⁻ is a counterion.

In certain embodiments, the carbon atom substituents are independently halogen, substituted or unsubstituted C₁₋₆ alkyl, —OR^(aa), —SR^(aa), —N(R^(bb))₂, —CN, —SCN, —NO₂, —C(═O)R^(aa), —CO₂R^(aa), —C(═O)N(R^(bb))₂, —OC(═O)R^(aa), —OCO₂R^(aa), —OC(═O)N(R^(bb))₂, —NR^(bb)C(═O)R^(aa), —NR^(bb)CO₂R^(aa), or —NR^(bb)C(═O)N(R^(bb))₂. In certain embodiments, the carbon atom substituents are independently halogen, substituted or unsubstituted C₁₋₆ alkyl, —OR^(aa), —SR^(aa), —N(R^(bb))₂, —CN, —SCN, or —NO₂.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing percent inhibition of the startle response to a 125 dB noise, when the startle noise is preceded by a light air puff in mice following i.p. administration of either saline or 2 mg/kg midazolam treatment. Two-way ANOVA with post-hoc Sidak's test, *, p<0.05. Advillin^(Cre) and Mecp^(2f/y) mice receiving vehicle treatment showed tactile hypersensitivity compared to control littermates. Treatment with midazolam significantly attenuated tactile sensitivity in both Mecp2 mutants and controls, with all mice exhibiting a decreased performance in tactile PPI.

FIG. 2 is a graph showing response to a light air puff stimulus alone in mice following i.p. administration of either saline or 2 mg/kg midazolam treatment. Responses are expressed as percent of startle response to a 125 dB noise. Two-way ANOVA with post-hoc Sidak's test, *, p<0.05.

FIG. 3 is a graph showing magnitude of startle response to a 125 dB noise in mice following i.p. administration of either saline or 2 mg/kg midazolam treatment. Responses are expressed as percent of startle response to a 125 dB noise. Two-way ANOVA with post-hoc Sidak's test, *, p<0.05. Although midazolam treatment reduced tactile sensitivity, this treatment also caused significant sedation in all mice, as evidenced by a ˜50% reduction in their startle amplitude.

FIG. 4 depicts the synthesis of Compound 1.

FIG. 5 depicts the syntheses of Compounds 2 and 3.

FIG. 6 depicts the synthesis of Compound 4.

FIG. 7 depicts the synthesis of Compound 5.

FIG. 8 depicts the synthesis of Compound 6.

DETAILED DESCRIPTION

A range of mouse genetic models of Autism Spectrum Disorder (ASD) combined with behavioral testing, synaptic analyses, and electrophysiology were used to define both the etiology of aberrant tactile sensitivity in ASD and the contribution of somatosensory dysfunction to the expression of ASD-like traits. In general, Mutations in genes associated with both syndromic and non-syndromic forms of ASD cause tactile dysfunction, and the Rett Syndrome (RTT)-, Phelan McDermid syndrome (PMS)-, and ASD-associated genes Mecp2, Shank3, and Gabrb3 function cell autonomously in peripheral somatosensory neurons for normal tactile behaviors. Abnormalities in tactile perception are observed in patients with Phelan McDermid Syndrome (PMS) and Fragile X syndrome, which are both highly associated with ASD and are caused by mutations in Shank3 and Fmr1, respectively Similarly, tactile hypersensitivity is common in patients with Rett syndrome (RTT), which is caused by mutations in the X-linked methyl-CpG-binding protein 2 (Mecp2) gene. Tactile dysfunction associated with Mecp2 and Gabrb3 ASD models is caused by a deficiency of the 03 subunit of the GABA_(A) receptor (GABRB3) and GABA_(A) receptor-mediated presynaptic inhibition (PSI) of somatosensory inputs to the CNS. Shank3 mutant DRG neurons, which are associated with PMS, on the other hand, exhibit hyperexcitability. These somatosensory deficits during development contribute to aberrant social behaviors as well as anxiety-like behaviors in adulthood. Somatosensory neuron dysfunction underlies aberrant tactile perception in ASD, RTT, PMS, and Fragile X syndrome and that functional so insufficiency of GABA_(A) receptors or hyperactivity of peripheral sensory neurons cause tactile processing deficiency during development, which leads to anxiety-like behavior and social interaction deficits in adult mice. Thus, peripheral sensory neurons represent exciting, untested therapeutic targets for ASD, RTT, PMS, and Fragile X syndrome.

Deficits in peripheral sensory neurons, and not neurons in the brain, account for touch hypersensitivity in mouse models of ASD. Moreover, touch hypersensitivity during development causes anxiety and social interaction deficits in adulthood. GABA_(A) receptor agonists, such as benzodiazepines, which attenuate the activity of peripheral mechanosensory neurons, may be useful for treating tactile hypersensitivity and thus anxiety and social impairments in ASD patients. However, treating young children with benzodiazepines has traditionally been avoided because of undesirable side effects of these drugs in children. Indeed, there is a general reluctance on the part of physicians to use FDA-approved benzodiazepines because of undesirable side effects, including sedation, and serious complications associated with interference with brain development.

Accordingly, the present invention provides peripherally-restricted benzodiazepines of Formulae (I)-(VII) (i.e., benzodiazepines exhibiting reduced blood brain barrier (BBB) permeability) and methods of use thereof, for reducing tactile dysfunction, social impairment, and/or anxiety in subjects in need thereof (e.g., in subjects diagnosed with ASD, RTT, PMS, or Fragile X syndrome).

Small Molecule Agents

Gamma-aminobutyrate (GABA) is synthesized primarily by the enzyme glutamate decarboxylase (GAD), which catalyzes the conversion of the excitatory neurotransmitter glutamate to GABA. GABA mediates a wide range of physiological functions, both in the CNS and in external tissues and organs, via binding to GABA receptor subtypes, GABA_(A) and GABA_(B). The most abundant subtype of GABA_(A) receptors are ionotropic receptors comprised of multiple subunits that form ligand-gated chloride ion channels. The GABA_(A) receptor subunits have been identified (alpha, beta, gamma, delta, epsilon, pi, and theta subunits), and each subunit is encoded by a separate gene. In addition, many subunits have multiple isoforms and/or splice variants, giving rise to a large degree of structural diversity.

Benzodiazepine compounds are positive allosteric modulators (PAMs) of the GABA_(A) receptor, i.e., they increase the activity of the GABA_(A) receptor protein in the vertebrate central nervous system. Upon binding the GABA_(A) receptor, benzodiazepnes trigger the receptor to open its chloride channel to allow chloride ions into the neuron, making the cell hyperpolarized and less likely to fire. GABA_(A) PAMs increase the effect of GABA by making the channel open more frequently or for longer periods. In psychopharmacology, GABA_(A) receptor PAMs used as drugs have mainly sedative and anxiolytic effects because the compounds cross the blood brain barrier and enter the central nervous system.

GABA_(A) PAMs, such as benzodiazepines, can be modified such that they retain GABA_(A) activity but can no longer penetrate the blood brain barrier, or such that they have reduced ability to permeate the blood brain barrier. Such compounds are “peripherally restricted,” i.e., they are restricted to the peripheral nervous system. Critically, the peripherally restricted benzodiazepine compounds disclosed herein maintain functionality as GABA_(A) PAMs. The compounds disclosed herein have structures and physiochemical properties that maintain or improve their therapeutic activity, but limit their exposure to the CNS. In some embodiments, the compounds disclosed herein have physiochemical properties, such as Log P (water-octanol partition coefficient) values, polar surface area (PSA) and/or freely rotatable bonds (FRBs), which limit the ability of the compounds to penetrate the blood brain barrier and enter the CNS.

Peripherally restricted GABA_(A) PAMs, such as peripherally restricted benzodiazepines cannot penetrate the blood brain barrier, or have reduced blood brain barrier permeability, and target GABA_(A) receptors in the peripheral nervous system. Such compounds can be administered to a subject with ASD, RTT, PMS, or Fragile X syndrome to reduce tactile dysfunction, social impairment, and anxiety, while avoiding unwanted central effects such as sedation.

The present disclosure provides novel, peripherally restricted benzodiazepine GABA_(A) receptor PAMs. A compound or pharmaceutically acceptable salt thereof of any one of Formulae (I)-(VII) (e.g., Compounds 1-5) may be administered to a subject to reduce social impairment, anxiety, or tactile dysfunction in patients diagnosed with ASD, RTT, PMS, or Fragile X syndrome. Exemplary compounds that may be used in the compositions and methods described herein are listed in Table 1.

TABLE 1 Compounds Compound Structure 1

2

3

4

5

6

Compounds that may be used in the compositions and methods described herein include any compound having the structure of Formula I:

or a pharmaceutically acceptable salt thereof, wherein:

R^(A) is R^(E), hydrogen, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —OR^(D1), —N(R^(D1a))₂, or —SR^(D1), wherein R^(D1) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom;

R^(B) is R^(E), hydrogen, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphaticl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group;

each instance of R^(C) and R^(D) is, independently, R^(E), hydrogen, halogen, nitro, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —OR^(D1a), —N(R^(D1a))₂, or —SR^(D1a), wherein R^(D1a) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom;

X is O, NR^(F), or CHR^(F);

p is 1, 2, 3, or 4;

n is 1, 2, 3, 4, or 5;

R^(E) is a moiety that restricts the compound of Formula (I) to the peripheral nervous system, provided that the compound of Formula (I) comprises at least one R^(E); and

R^(F) is a nitrogen radical that combines with R^(B) to form a fused 5-membered heterocyclyl or heteroaryl ring.

In certain embodiments, Formula (I) comprises the substituent R^(A). In certain embodiments, R^(A) is replaced with the substituent R^(E). In certain embodiments, R^(A) is hydrogen. In certain embodiments, R^(A) is optionally substituted acyl. In certain embodiments, R^(A) is optionally substituted aliphatic. In certain embodiments, R^(A) is optionally substituted heteroaliphatic. In certain embodiments, R^(A) is optionally substituted carbocyclyl. In certain embodiments, R^(A) is optionally substituted heterocyclyl. In certain embodiments, R^(A) is optionally substituted aryl. In certain embodiments, R^(A) is optionally substituted heteroaryl. In certain embodiments, R^(A) is —OR^(D1), wherein R^(D1) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom. In certain embodiments, R^(A) is —N(R^(D1a))₂. In certain embodiments, R^(A) is —SR^(D1).

In certain embodiments, Formula (I) comprises the substituent R^(B). In certain embodiments, R^(B) is replaced with the substituent R^(E). In certain embodiments, R^(B) is hydrogen. In certain embodiments, R^(B) is optionally substituted acyl. In certain embodiments, R^(B) is optionally substituted aliphatic. In certain embodiments, R^(B) is optionally substituted alkyl. In certain embodiments, R^(B) is optionally substituted methyl. In certain embodiments, R^(B) is unsubstituted methyl. In certain embodiments, R^(B) is optionally substituted heteroaliphatic. In certain embodiments, R^(B) is optionally substituted carbocyclyl. In certain embodiments, R^(B) is optionally substituted heterocyclyl. In certain embodiments, R^(B) is optionally substituted aryl. In certain embodiments, R^(B) is optionally substituted heteroaryl. In certain embodiments, R^(B) is a nitrogen protecting group.

In certain embodiments, Formula (I) comprises the substituents R^(C) and R^(D). In certain embodiments, R^(C) is replaced with the substituent R^(E). In certain embodiments, R^(D) is replaced with the substituent R^(E). In certain embodiments, Formula (I) comprises the substituent R^(C), and R^(D) is replaced with the substituent R^(E). In certain embodiments, Formula (I) comprises the substituent R^(D), and R^(C) is replaced with the substituent R^(E). In certain embodiments, R^(C) and R^(D) are the same. In certain embodiments, R^(C) and R^(D) are different.

In certain embodiments, Formula (I) comprises n instances of R^(C). In certain embodiments, n is 1. In certain embodiments, n is 2. In certain embodiments, n is 3. In certain embodiments, n is 4. In certain embodiments, n is 5. In certain embodiments, R^(C) is hydrogen. In certain embodiments, R^(C) is halogen. In certain embodiments, R^(C) is nitro. In certain embodiments, R^(C) is optionally substituted acyl. In certain embodiments, R^(C) is optionally substituted aliphatic. In certain embodiments, R^(C) is optionally substituted heteroaliphatic In certain embodiments, R^(C) is optionally substituted carbocyclyl. In certain embodiments, R^(C) is optionally substituted heterocyclyl. In certain embodiments, R^(C) is optionally substituted aryl. In certain embodiments, R^(C) is optionally substituted heteroaryl. In certain embodiments, R^(C) is —OR^(D1a), wherein R^(D1a) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom. In certain embodiments, R^(C) is —N(R^(D1a))₂. In certain embodiments, R^(C) is —SR^(D1a).

In certain embodiments, Formula (I) comprises p instances of R^(D). In certain embodiments, p is 1. In certain embodiments, p is 2. In certain embodiments, p is 3. In certain embodiments, p is 4. In certain embodiments, R^(D) is hydrogen. In certain embodiments, R^(D) is halogen. In certain embodiments, R^(D) is nitro. In certain embodiments, R^(D) is optionally substituted acyl. In certain embodiments, R^(D) is optionally substituted aliphatic. In certain embodiments, R^(D) is optionally substituted heteroaliphatic In certain embodiments, R^(D) is optionally substituted carbocyclyl. In certain embodiments, R^(D) is optionally substituted heterocyclyl. In certain embodiments, R^(D) is optionally substituted aryl. In certain embodiments, R^(D) is optionally substituted heteroaryl. In certain embodiments, R^(D) is —OR^(D1a), wherein R^(D1a) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom. In certain embodiments, R^(C) is —N(R^(D1a))₂. In certain embodiments, R^(C) is —SR^(D1a).

Formula (I) comprises the substituent X. In certain embodiments, X is O. In certain embodiments, X is NR^(F), wherein R^(F) is a nitrogen radical that combines with R^(B) to form a fused 5-membered heterocyclyl or heteroaryl ring. In certain embodiments, X is CHR^(F).

Formula (I) comprises the substituent R^(E). The subsistent R^(E) is a moiety that restricts the compound of Formula (I) to the peripheral nervous system. In certain embodiments, R^(E) is optionally substituted C₁₋₅₀ heteroaliphatic. In certain embodiments, R^(E) is —OR^(E1), wherein R^(E1) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom. In certain embodiments, R^(E) is —N(R^(E1))₂. In certain embodiments, R^(E) is —NO₂. In certain embodiments, R^(E) is —CN. In certain embodiments, R^(E) is —SR^(E1). In certain embodiments, R^(E) is —CH₂OR^(E1). In certain embodiments, R^(E) is —CH₂N(R^(E1))₂. In certain embodiments, R^(E) is —CH₂SR^(E1). In certain embodiments, R^(E) is —NR^(E1)C(═O)R^(E1). In certain embodiments, R^(E) is —C(═O)N(R^(E1))₂. In certain embodiments, R^(E) is —SC(═O)R^(E1). In certain embodiments, R^(E) is —C(═O)SR^(E1). In certain embodiments, R^(E) is —OC(═O)R^(E1). In certain embodiments, R^(E) is —C(═O)OR^(E1). In certain embodiments, R^(E) is —NR^(E)C(═S)R^(E1). In certain embodiments, R^(E) is —C(═S)NR^(E1). In certain embodiments, R^(E) is rans-CR^(E1)═CR^(E1). In certain embodiments, R^(E) is as —CR^(E1)═CR^(E1). In certain embodiments, R^(E) is —C≡C—R^(E1). In certain embodiments, R^(E) is —S(═O)R^(E1). In certain embodiments, R^(E) is —S(═O)OR^(E1). In certain embodiments, R^(E) is —OS(═O)R^(E1). In certain embodiments, R^(E) is —S(═O)N(R^(E1))₂. In certain embodiments, R^(E) is —NR^(E1)S(═O)R^(E1). In certain embodiments, R^(E) is —S(═O)₂R^(E1). In certain embodiments, R^(E) is —S(═O)₂OR^(E1). In certain embodiments, R^(E) is —OS(═O)₂R^(E1). In certain embodiments, R^(E) is —S(═O)₂N(R^(E1))₂R^(E1). In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is —OR^(E1), —N(R^(E1))₂, —CH₂N(R^(E1))₂, or —C(═O)N(R^(E1))₂.

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In certain embodiments, R^(E) is of the formula:

In some embodiments, Formula (I) has the structure of Formula (II):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (III):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (IV):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (V):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IIa):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IIb):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IIc):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (II) has the structure of Formula (IId):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (VI):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (I) has the structure of Formula (VII):

or a pharmaceutically acceptable salt thereof.

In some embodiments, compounds of Formulae (I) and (II) have a structure selected from:

and pharmaceutically acceptable salts thereof.

In some embodiments, Formula (III) has the structure of Formula (IIIa):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (III) has the structure of Formula (IIIb):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (III) has the structure of Formula (IIIc):

or a pharmaceutically acceptable salt thereof.

In some embodiments, Formula (III) has the structure of Formula (IIId):

or a pharmaceutically acceptable salt thereof.

In some embodiments, a compound of Formula (III) has a structure selected from:

and pharmaceutically acceptable salts thereof.

Indications

The compounds described herein are useful in treating tactile dysfunction, anxiety, and social impairment in a subject diagnosed with ASD, RTT, PMS, or Fragile X syndrome.

Tactile Dysfunction

Tactile dysfunction includes exhibiting symptoms such as withdrawing when being touched, refusing to eat certain “textured” foods and/or to wear certain types of clothing, complaining about having hair or face washed, avoiding getting hands dirty (e.g., glue, sand, mud, finger-paint), and using finger tips rather than whole hands to manipulate objects. Tactile dysfunction may lead to a misperception of touch and/or pain (hyper- or hyposensitive) and may lead to self-imposed isolation, general irritability, distractibility, and hyperactivity.

Anxiety

Anxiety includes emotions characterized by feelings of tension, worried thoughts and physical changes like increased blood pressure. Anxiety can be characterized by having recurring intrusive thoughts or concerns, avoiding certain situations (e.g., social situations) out of worry, and physical symptoms such as sweating, trembling, dizziness or a rapid heartbeat.

Social Impairment

Social impairment involves a distinct dissociation from and lack of involvement in relations with other people. It can occur with various mental and developmental disorders, such as autism. Social impairment may occur when an individual acts in a less positive way or performs worse when they are around others as compared to when alone. Nonverbal behaviors associated with social impairment can include deficits in eye contact, facial expression, and gestures that are used to help regulate social interaction. Often there is a failure to develop age-appropriate friendships. Social impairment can also include a lack of spontaneous seeking to share achievements or interests with other individuals. A person with social impairment may exhibit a deficit in social reciprocity with individuals, decreased awareness of others, lack of empathy, and lack of awareness of the needs of others.

Autism Spectrum Disorder

ASD is a heterogeneous group of neurodevelopmental disorders as classified in the fifth revision of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders 5^(th) edition (DSM-5). The DSM-5 redefined the autism spectrum to encompass the prior (DSM-IV-TR) diagnosis of autism, Asperger syndrome, pervasive developmental disorder not otherwise specified, childhood disintegrative disorder, and Rett syndrome. The autism spectrum disorders are characterized by social deficits and communication difficulties, stereotyped or repetitive behaviors and interests, and in some cases, cognitive delays. For example, an ASD is defined in the DSM-5 as exhibiting (i) deficits in social communication and interaction not caused by general developmental delays (must exhibit three criteria including deficits in social-emotional reciprocity, deficits in nonverbal communication, and deficits in creating and maintaining relationships appropriate to developmental level), (ii) demonstration of restricted and repetitive patterns of behavior, interest or activities (must exhibit two of the following four criteria: repetitive speech, repetitive motor movements or repetitive use of objects, adherence to routines, ritualized patterns of verbal or nonverbal, or strong resistance to change, fixated interests that are abnormally intense of focus, and over or under reactivity to sensory input or abnormal interest in sensory aspects of environment), (iii) symptoms must be present in early childhood, and (iv) symptoms collectively limit and hinder everyday functioning. ASD is also contemplated herein to include Dravet's syndrome and autistic-like behavior in non-human animals.

Rett Syndrome

Rett syndrome is an X-linked disorder that affects approximately one in ten-thousand girls. Patients go through four stages: Stage I) Following a period of apparently normal development from birth, the child begins to display social and communication deficits, similar to those seen in other autism spectrum disorders, between six and eighteen months of age. The child shows delays in their developmental milestones, particularly for motor ability, such as sitting and crawling. Stage II) Beginning between one and four years of age, the child goes through a period of regression in which they lose speech and motor abilities, developing stereotypical midline hand movements and gait impairments. Breathing irregularities, including apnea and hyperventilation also develop during this stage. Autistic symptoms are still prevalent at this stage. Stage III) Between age two and ten, the period of regression ends and symptoms plateau. Social and communication skills may show small improvements during this plateau period, which may last for most of the patients' lives. Stage IV) Motor ability and muscle deterioration continues. Many girls develop severe scoliosis and lose the ability to walk.

Phelan McDermid syndrome

Phelan McDermid syndrome is a rare genetic condition caused by a deletion or other structural change of the terminal end of chromosome 22 in the 22q13 region or a disease-causing mutation of the Shank3 gene. Although the range and seventy of symptoms may vary, PMS is generally thought to be characterized by neonatal hypotonia (low muscle tone in the newborn), normal growth, absent to severely delayed speech, moderate to profound developmental delay, and minor dysmorphic provides. People who have PMS often show symptoms in very early childhood, sometimes at birth and within the first six months of life.

Fragile X Syndrome

Fragile X syndrome is an X chromosome-linked condition that is characterized by a visible constriction near the end of the X chromosome, at locus q27.3 that causes intellectual disability, behavioral and learning challenges and various physical characteristics Fragile X syndrome is the most common inherited form of mental retardation and developmental disability. Males with Fragile X syndrome usually have mental retardation and often exhibit characteristic physical provides and behavior. Fragile X syndrome is characterized by behavior similar to autism and attention deficit disorder, obsessive-compulsive tendencies, hyperactivity, slow development of motor skills and anxiety fear disorder. When these disabilities are severe and occur simultaneously, the condition is sometimes described as autism, and may be associated with any degree of intelligence. Other characteristics are a likable, happy, friendly personality with a limited number of autistic-like provides such as hand-flapping, finding direct eye contact unpleasant, and some speech and language problems. Physical provides may include large ears, long face, soft skin and large testicles (called “macroorchidism”) in post-pubertal males. Connective tissue problems may include ear infections, flat feet, high arched palate, double-jointed fingers and hyper-flexible joints.

Pharmaceutical Compositions

The compounds described herein (e.g., the compounds of Formulae (I)-(VII), e.g., the compounds of Table 1, and pharmaceutically acceptable salts thereof) may be formulated into pharmaceutical compositions for administration to human subjects in a biologically compatible form suitable for administration in vivo. Pharmaceutical compositions typically include an active agent and a pharmaceutically acceptable excipient.

The compound can also be used in the form of the free base, in the form of salts, zwitterions, solvates, or as prodrugs, or pharmaceutical compositions thereof. All forms are within the scope of the invention. The compounds, salts, zwitterions, solvates, prodrugs, or pharmaceutical compositions thereof, may be administered to a patient in a variety of forms depending on the selected route of administration, as will be understood by those skilled in the art. The compounds described herein may be administered, for example, by oral, parenteral, buccal, sublingual, nasal, rectal, patch, pump, or transdermal administration, and the pharmaceutical compositions formulated accordingly. Parenteral administration includes intravenous, intraperitoneal, subcutaneous, intramuscular, transepithelial, nasal, intrapulmonary, intrathecal, rectal, and topical modes of administration. Parenteral administration may be by continuous infusion over a selected period of time.

For human use, the compounds described herein can be administered alone or in admixture with a pharmaceutical carrier selected with regard to the intended route of administration and standard pharmaceutical practice. Pharmaceutical compositions for use in accordance with the present invention thus can be formulated in a conventional manner using one or more physiologically acceptable carriers including excipients and auxiliaries that facilitate processing of compounds into preparations which can be used pharmaceutically.

The excipient or carrier is selected on the basis of the mode and route of administration. Suitable pharmaceutical carriers, as well as pharmaceutical necessities for use in pharmaceutical formulations, are described in Remington: The Science and Practice of Pharmacy, 22nd Ed., Allen, Ed. (2012), a well-known reference text in this field, and in the USP/NF (United States Pharmacopeia and the National Formulary). Examples of suitable excipients are lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, alginates, tragacanth, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrup, and methyl cellulose. The formulations can additionally include: lubricating agents, e.g., talc, magnesium stearate, and mineral oil; wetting agents; emulsifying and suspending agents; preserving agents, e.g., methyl- and propylhydroxy-benzoates; sweetening agents; and flavoring agents. Other exemplary excipients are described in Handbook of Pharmaceutical Excipients, 6th Edition, Rowe et al., Eds., Pharmaceutical Press (2009).

These pharmaceutical compositions can be manufactured in a conventional manner, e.g., by conventional mixing, dissolving, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping, or lyophilizing processes. Methods well known in the art for making formulations are found, for example, in Remington: The Science and Practice of Pharmacy, 22nd Ed., Allen, Ed. (2012), and Encyclopedia of Pharmaceutical Technology, eds. J. Swarbrick and J. C. Boylan, 1988-1999, Marcel Dekker, New York. Proper formulation is dependent upon the route of administration chosen. The formulation and preparation of such compositions is well-known to those skilled in the art of pharmaceutical formulation. In preparing a formulation, the active compound can be milled to provide the appropriate particle size prior to combining with the other ingredients. If the active compound is substantially insoluble, it can be milled to a particle size of less than 200 mesh. If the active compound is substantially water soluble, the particle size can be adjusted by milling to provide a substantially uniform distribution in the formulation, e.g., about 40 mesh.

Dosages

The dosage of the compounds described herein (e.g., the compounds of Formulae (I)-(VII), e.g., the compounds of Table 1, and pharmaceutically acceptable salts thereof), or pharmaceutically acceptable salts or prodrugs thereof, or pharmaceutical compositions thereof, can vary depending on many factors, e.g., the pharmacodynamic properties of the compound, the mode of administration, the age, health, and weight of the recipient, the nature and extent of the symptoms, the frequency of the treatment, and the type of concurrent treatment, if any, and the clearance rate of the composition in the subject to be treated. One of skill in the art can determine the appropriate dosage based on the above factors. The active agent may be administered initially in a suitable dosage that may be adjusted as required, depending on the clinical response. In general, a suitable daily dose of an active agent will be that amount of the compound that is the lowest dose effective to produce a therapeutic effect. Such an effective dose will generally depend upon the factors described above.

In general, the dosage of a pharmaceutical composition or the active agent in a pharmaceutical composition may be in the range of from about 1 pg to about 10 g (e.g., 1 pg-10 pg, e.g., 2 pg, 3 pg, 4 pg, 5 pg, 6 pg, 7 pg, 8 pg, 9 pg, 10 pg, e.g., 10 pg-100 pg, e.g., 20 pg, 30 pg, 40 pg, 50 pg, 60 pg, 70 pg, 80 pg, 90 pg, 100 pg, e.g., 100 pg-1 ng, e.g., 200 pg, 300 pg, 400 pg, 500 pg, 600 pg, 700 pg, 800 pg, 900 pg, 1 ng, e.g., 1 ng-10 ng, e.g., 2 ng, 3 ng, 4 ng, 5 ng, 6 ng, 7 ng, 8 ng, 9 ng, 10 ng, e.g., 10 ng-100 ng, e.g., 20 ng, 30 ng, 40 ng, 50 ng, 60 ng, 70 ng, 80 ng, 90 ng, 100 ng, e.g., 100 ng-1 pg, e.g., 200 ng, 300 ng, 400 ng, 500 ng, 600 ng, 700 ng, 800 ng, 900 ng, 1 μg, e.g., 1-10 μg, e.g., 1 μg, 2 μg, 3 μg, 4 μg, 5 μg, 6 μg, 7 μg, 8 μg, 9 μg, 10 μg, e.g., 10 μg-100 μg, e.g., 20 μg, 30 μg, 40 μg, 50 μg, 60 μg, 70 μg, 80 μg, 90 μg, 100 μg, e.g., 100 μg-1 mg, e.g., 200 μg, 300 μg, 400 μg, 500 μg, 600 μg, 700 μg, 800 μg, 900 μg, 1 mg, e.g., 1 mg-10 mg, e.g., 2 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7 mg, 8 mg, 9 mg, 10 mg, e.g., 10 mg-100 mg, e.g., 20 mg, 30 mg, 40 mg, 50 mg, 60 mg, 70 mg, 80 mg, 90 mg, 100 mg, e.g., 100 mg-1 g, e.g., 200 mg, 300 mg, 400 mg, 500 mg, 600 mg, 700 mg, 800 mg, 900 mg, 1 g, e.g., 1 g-10 g, e.g., 2 g, 3 g, 4 g, 5 g, 6 g, 7 g, 8 g, 9 g, 10 g).

The pharmaceutical composition or the active agent may also be administered as a unit dose form or as a dose per mass or weight of the patient from about 0.01 mg/kg to about 100 mg/kg (e.g., 0.01-0.1 mg/kg, e.g., 0.02 0.03 mg/kg, 0.04 mg/kg, 0.05 mg/kg, 0.06 mg/kg, 0.07 mg/kg, 0.08 mg/kg, 0.09 mg/kg, 0.1 mg/kg, e.g., 0.1-1 mg/kg, e.g., 0.2 mg/kg, 0.3 mg/kg, 0.4 mg/kg, 0.5 mg/kg, 0.6 mg/kg, 0.7 mg/kg, 0.8 mg/kg, 0.9 mg/kg, 1 mg/kg, e.g., 1-10 mg/kg, e.g., 1 mg/kg, 2 mg/kg, 3 mg/kg, 4 mg/kg, 5 mg/kg, 6 mg/kg, 7 mg/kg, 8 mg/kg, 9 mg/kg, 10 mg/kg, e.g., 10-100 mg/kg, e.g., 20 mg/kg, 30 mg/kg, 40 mg/kg, 50 mg/kg, 60 mg/kg, 70 mg/kg, 80 mg/kg, 90 mg/kg, 100 mg/kg). The dose may also be administered as a dose per mass or weight of the patient per unit day (e.g., 0.1-10 mg/kg/day).

The dosage regimen may be determined by the clinical indication being addressed (e.g., ASD, RTT, PMS, or Fragile X syndrome, e.g., social impairment or anxiety), as well as by various patient variables (e.g., weight, age, sex) and clinical presentation (e.g., extent or severity of tactile sensitivity, anxiety, or social impairment). Furthermore, it is understood that all dosages may be continuously given or divided into dosages given per a given time frame. The composition may be administered, for example, every hour, day, week, month, or year.

Formulations

The compounds described herein may be administered to patients or animals with a pharmaceutically acceptable diluent, carrier, or excipient, in unit dosage form. The compounds for use in treatment of ASD, RTT, PMS, or Fragile X syndrome may be produced and isolated by any standard technique known to those in the field of medicinal chemistry. Conventional pharmaceutical practice may be employed to provide suitable formulations or compositions to administer the compound to patients diagnosed with ASD, RTT, PMS, or Fragile X syndrome.

Exemplary routes of administration of the compounds, or pharmaceutical compositions thereof, used in the present invention include oral, sublingual, buccal, transdermal, intradermal, intramuscular, parenteral, intravenous, intra-arterial, intracranial, subcutaneous, intraorbital, intraventricular, intraspinal, intraperitoneal, intranasal, inhalation, intrathecal and topical administration. The compounds may be administered with a pharmaceutically acceptable carrier.

Formulations for Oral Administration

The pharmaceutical compositions contemplated by the invention include those formulated for oral administration. Oral dosage forms can be, for example, in the form of tablets, capsules, a liquid solution or suspension, a powder, or liquid or solid crystals, which contain the active ingredient(s) in a mixture with non-toxic pharmaceutically acceptable excipients. These excipients may be, for example, inert diluents or fillers (e.g., sucrose, sorbitol, sugar, mannitol, microcrystalline cellulose, starches including potato starch, calcium carbonate, sodium chloride, lactose, calcium phosphate, calcium sulfate, or sodium phosphate), granulating and disintegrating agents (e.g., cellulose derivatives including microcrystalline cellulose, starches including potato starch, croscarmellose sodium, alginates, or alginic acid), binding agents (e.g., sucrose, glucose, sorbitol, acacia, alginic acid, sodium alginate, gelatin, starch, pregelatinized starch, microcrystalline cellulose, magnesium aluminum silicate, carboxymethylcellulose sodium, methylcellulose, hydroxypropyl methylcellulose, ethylcellulose, polyvinylpyrrolidone, or polyethylene glycol), and lubricating agents, glidants, and antiadhesives (e.g., magnesium stearate, zinc stearate, stearic acid, silicas, hydrogenated vegetable oils, or talc). Other pharmaceutically acceptable excipients can be colorants, flavoring agents, plasticizers, humectants, buffering agents, and the like.

Formulations for oral administration may also be presented as chewable tablets, as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent (e.g., potato starch, lactose, microcrystalline cellulose, calcium carbonate, calcium phosphate or kaolin), or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example, peanut oil, liquid paraffin, or olive oil. Powders, granulates, and pellets may be prepared using the ingredients mentioned above under tablets and capsules in a conventional manner using, e.g., a mixer, a fluid bed apparatus or a spray drying equipment.

Controlled release compositions for oral use may be constructed to release the active drug by controlling the dissolution and/or the diffusion of the active drug substance. Any of a number of strategies can be pursued in order to obtain controlled release and the targeted plasma concentration versus time profile. In one example, controlled release is obtained by appropriate selection of various formulation parameters and ingredients, including, e.g., various types of controlled release compositions and coatings. Examples include single or multiple unit tablet or capsule compositions, oil solutions, suspensions, emulsions, microcapsules, microspheres, nanoparticles, patches, and liposomes. In certain embodiments, compositions include biodegradable, pH, and/or temperature-sensitive polymer coatings.

Dissolution or diffusion-controlled release can be achieved by appropriate coating of a tablet, capsule, pellet, or granulate formulation of the compounds described herein, or by incorporating the compound into an appropriate matrix. A controlled release coating may include one or more of the coating substances mentioned above and/or, e.g., shellac, beeswax, glycowax, castor wax, carnauba wax, stearyl alcohol, glyceryl monostearate, glyceryl distearate, glycerol palmitostearate, ethylcellulose, acrylic resins, dl-polylactic acid, cellulose acetate butyrate, polyvinyl chloride, polyvinyl acetate, vinyl pyrrolidone, polyethylene, polymethacrylate, methylmethacrylate, 2-hydroxymethacrylate, methacrylate hydrogels, 1,3 butylene glycol, ethylene glycol methacrylate, and/or polyethylene glycols. In a controlled release matrix formulation, the matrix material may also include, e.g., hydrated methylcellulose, carnauba wax and stearyl alcohol, carbopol 934, silicone, glyceryl tristearate, methyl acrylate-methyl methacrylate, polyvinyl chloride, polyethylene, and/or halogenated fluorocarbon.

The liquid forms in which the compounds and compositions of the present invention can be incorporated for administration orally include aqueous solutions, suitably flavored syrups, aqueous or oil suspensions, and flavored emulsions with edible oils, e.g., cottonseed oil, sesame oil, coconut oil, or peanut oil, as well as elixirs and similar pharmaceutical vehicles.

Formulations for Parenteral Administration

The compounds described herein can be administered in a pharmaceutically acceptable parenteral (e.g., intravenous or intramuscular) formulation as described herein. The pharmaceutical formulation may also be administered parenterally (intravenous, intramuscular, subcutaneous or the like) in dosage forms or formulations containing conventional, non-toxic pharmaceutically acceptable carriers and adjuvants. In particular, formulations suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain anti-oxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient, and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. For example, to prepare such a composition, the compounds may be dissolved or suspended in a parenterally acceptable liquid vehicle. Among acceptable vehicles and solvents that may be employed are water, water adjusted to a suitable pH by addition of an appropriate amount of hydrochloric acid, sodium hydroxide or a suitable buffer, 1,3-butanediol, Ringer's solution and isotonic sodium chloride solution. The aqueous formulation may also contain one or more preservatives, for example, methyl, ethyl, or n-propyl p-hydroxybenzoate. Additional information regarding parenteral formulations can be found, for example, in the United States Pharmacopeia-National Formulary (USP-NF), herein incorporated by reference.

Exemplary formulations for parenteral administration include solutions of the compound prepared in water suitably mixed with a surfactant, e.g., hydroxypropylcellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, DMSO and mixtures thereof with or without alcohol, and in oils. Under ordinary conditions of storage and use, these preparations may contain a preservative to prevent the growth of microorganisms. Conventional procedures and ingredients for the selection and preparation of suitable formulations are described, for example, in Remington: The Science and Practice of Pharmacy, 22nd Ed., Allen, Ed. (2012) and in The United States Pharmacopeia: The National Formulary (USP 36 NF31), published in 2013.

Formulations for parenteral administration may, for example, contain excipients, sterile water, or saline, polyalkylene glycols, e.g., polyethylene glycol, oils of vegetable origin, or hydrogenated napthalenes. Biocompatible, biodegradable lactide polymer, lactide/glycolide copolymer, or polyoxyethylene-polyoxypropylene copolymers may be used to control the release of the compounds. Other potentially useful parenteral delivery systems for the compounds described herein include ethylene-vinyl acetate copolymer particles, osmotic pumps, implantable infusion systems, and liposomes. Formulations for inhalation may contain excipients, for example, lactose, or may be aqueous solutions containing, for example, polyoxyethylene-9-lauryl ether, glycocholate and deoxycholate, or may be oily solutions for administration in the form of nasal drops, or as a gel.

The parenteral formulation can be formulated for prompt release or for sustained/extended release of the compound. Exemplary formulations for parenteral release of the compound include aqueous solutions, powders for reconstitution, cosolvent solutions, oil/water emulsions, suspensions, oil-based solutions, liposomes, microspheres, and polymeric gels.

EXAMPLES

The compounds described herein are synthesized according to the known methods. All starting materials are available commercially or are prepared according to procedures known to one of skill in the art.

Example 1. Synthesis of Compound 1 General Procedure for Preparation of Compound 7-4B

With reference to FIG. 4, to a solution of compound 7-3 (1.00 g, 3.51 mmol, 1.00 eq) in THF (20.0 mL) was added LDA (2.00 M, 5.27 mL, 3.00 eq) at −78° C. The mixture was stirred at −78° C. for 1 hr. Next, a solution of compound 3A (1.27 g, 10.54 mmol, 3.00 eq) in THF (5.00 mL) was added at −25° C. and the mixture was stirred at −25° C. for 3 hr. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.63) indicated compound 7-3 was consumed completely and one major new spot with lower polarity was detected. The reaction mixture was quenched by addition H₂O (50.0 mL) at 25° C., and then extracted with EtOAc (40.0 mL, 20.0 mL, 10.0 mL). The combined organic layers were dried over Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The residue was purified by column chromatography (SiO₂, Petroleum ether:Ethyl acetate=40:1 to 2:1). Compound 7-4B (700 mg, 2.16 mmol, 61.4% yield) was obtained as a yellow solid. ¹H NMR: 400 MHz CDCl₃ δ 7.59-7.61 (m, 2H), 7.42-7.54 (m, 4H), 7.27-7.32 (m, 2H), 5.95-6.04 (m, 1H), 5.16-5.21 (m, 1H), 5.08-5.11 (m, 1H), 3.60 (s, 1H), 3.42 (s, 3H), 3.02 (br s, 1H).

General Procedure for Preparation of Compound 7-4C

To a solution of compound 7-4B (600 mg, 1.85 mmol, 1.00 eq) in DCM (20.0 mL) at −78° C. and the mixture was bubbled with 03 until turned blue. Next, the mixture was bubbled with 02 for 5 min and PPh₃ (969 mg, 3.69 mmol, 2.00 eq) was added at −78° C. The mixture was stirred at 25° C. for 3 h. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.47) indicated compound 7-4B was consumed completely and one major new spot with larger polarity was detected. The reaction mixture of compound 7-4C (604 mg, 1.85 mmol, 99.99% theory yield) was used into the next step without further work up.

General Procedure for Preparation of Compound 7-5A

The reaction mixture of compound 7-4C (604 mg, 1.85 mmol, 1.00 eq) were added MeOH (2.00 mL) and NaBH₄ (1045 mg, 2.77 mmol, 1.50 eq). The mixture was stirred at 25° C. for 1 h. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.22) indicated compound 7-4C was consumed completely and one new spot formed. The reaction mixture was concentrated under reduced pressure to remove solvent. The residue was purified by column chromatography (SiO₂, Petroleum ether:Ethyl acetate=25:1 to 5:1). Compound 7-5A (500 mg, 1.52 mmol, 82.3% yield) was obtained as a light yellow solid. ¹H NMR: 400 MHz CDCl₃. δ 7.56-7.58 (m, 2H), 7.52-7.56 (m, 2H), 7.42-7.44 (m, 2H), 7.30-7.33 (m, 2H), 3.96-4.02 (m, 2H), 3.84 (t, J=6.40 Hz, 1H), 3.42 (s, 3H), 2.97 (br s, 1H), 2.53-2.55 (m, 1H), 2.40-2.42 (m, 1H).

General Procedure for Preparation of Compound 7-6B

To a solution of compound 7-5A (360 mg, 1.09 mmol, 1.00 eq) and TEA (332 mg, 3.28 mmol, 457 μL, 3.00 eq) in DCM (4.00 mL) was added MsCl (188 mg, 1.64 mmol, 127 uL, 1.50 eq) at 0° C.

The mixture was stirred at 0° C. for 1 hr. TLC (Dichloromethane:Methanol=10:1, R_(f)=0.56) indicated compound 7-5A was consumed completely and one new spot formed. The reaction mixture was concentrated under reduced pressure to remove solvent. The residue was purified by prep-TLC (SiO₂, DCM:MeOH=10:1). Compound 7-6B (330 mg, 811 umol, 74.1% yield) was obtained as a yellow oil. ¹H NMR: 400 MHz CDCl₃. δ 7.62 (d, J=7.20 Hz, 2H), 7.54-7.58 (m, 1H), 7.45-7.50 (m, 1H), 7.45 (d, J=8.00 Hz, 2H), 7.32-7.34 (m, 2H), 4.64-4.66 (m, 1H), 4.55-4.59 (m, 1H), 3.77-3.81 (m, 1H), 3.44 (s, 3H), 2.96 (s, 3H), 2.69-2.73 (m, 1H), 2.60-2.64 (m, 1H).

General Procedure for Preparation of Compound 7-7

To a solution of compound 7-6B (330 mg, 811.05 umol, 1.00 eq) in acetone (4 mL) was added NaI (365 mg, 2.43 mmol, 3.00 eq). The mixture was stirred at 70° C. for 3 hr. TLC (Petroleum ether:Ethyl acetate=2:1, R_(f)=0.62) indicated compound 7-6B was consumed completely and one new spot formed. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure to remove solvent. The crude product compound 7-7 (320 mg, crude) was used into the next step without further purification as yellow solid.

General Procedure for Preparation of Compound Target 7 (Compound 1)

The mixture of compound 7-7 (300 mg, 684 umol, 1.00 eq) in MeNH₂/THF (2 M, 3.00 mL, 8.77 eq) was stirred at 25° C. for 4 hr. LC-MS showed compound 7-7 was consumed completely and one main peak with desired mass was detected. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure to remove solvent. The residue was purified by prep-HPLC (neutral condition:column:Waters Xbridge Prep OBD C18 150*40 mm*10 μm; mobile phase: [water (10 mM NH₄HCO₃)-ACN]; B %: 20%-50%, 8 min). Target 7 (Compound 1) (80.0 mg, 234 μmol, 34.2% yield) was obtained as a light yellow solid. ¹H NMR: 400 MHz CDCl₃. δ 7.60 (br d, J=6.80 Hz, 2H), 7.42-7.51 (m, 4H), 7.29-7.31 (m, 2H), 3.67 (dd, J=7.60, 6.00 Hz, 1H), 3.41 (s, 3H), 2.77-2.84 (m, 2H), 2.36-2.44 (m, 5H). LC/MS: (M⁺H⁺)=342.1. HPLC: RT=2.117.

Example 2. Synthesis of Compounds 2 and 3 General Procedure for Preparation of Compound 7-2

With reference to FIG. 5, a mixture of compound 7-1 (5.00 g, 20.3 mmol, 1.00 eq), 2-chloroacetyl chloride (34.5 g, 305 mmol, 24.3 mL, 15.0 eq) was degassed and purged with N₂ for 3 times, and then the mixture was stirred at 25° C. for 5 hrs under N₂ atmosphere. TLC (Petroleum ether:Ethyl acetate=2:1, R_(f)=0.45) indicated compound 7-1 was consumed completely and two new spots formed. The reaction mixture was quenched by addition H₂O (80 mL), and then diluted with EtOAc (50 mL) and extracted with EtOAc (30 mL, 20 mL, 10 mL). The combined organic layers were washed with brine (30 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The residue was purified by column chromatography (SiO₂, Petroleum ether:Ethyl acetate=10:1). Compound 7-2 (6.20 g, 19.2 mmol, 94.5% yield) was obtained as a yellow solid. ¹H NMR: 400 MHz CDCl₃, δ 7.81 (d, J=7.60 Hz, 2H), 7.62-7.79 (m, 2H), 7.48-7.51 (m, 3H), 7.39-7.41 (m, 1H), 3.87-3.99 (m, 2H), 3.07 (s, 3H).

General Procedure for Preparation of Compound 7-3

To a solution of compound 7-2 (6.20 g, 19.2 mmol, 1.00 eq) was added 6,7,8,9-tetrazatricyclodecane (1.35 g, 9.62 mmol, 1.80 mL, 0.50 eq), and NH₃/MeOH (7.00 M, 2.75 mL, 1.00 eq). The mixture was stirred at 60° C. for 6 hrs. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.43) indicated compound 7-2 was consumed completely and many new spots formed. The reaction mixture was concentrated under reduced pressure. The residue was purified by column chromatography (SiO₂, Petroleum ether/Ethyl acetate=20/1). Compound 7-3 (3.20 g, 11.2 mmol, 58.4% yield) was obtained as a yellow solid. ¹H NMR: 400 MHz CDCl₃, δ 7.54 (d, J=7.20 Hz, 2H), 7.34-7.43 (m, 4H), 7.19-7.23 (m, 2H), 4.78 (d, J=10.8 Hz, 1H), 3.71 (d, J=10.8 Hz, 1H), 3.32 (s, 3H).

General Procedure for Preparation of Compound 7-4

To a solution of compound 7-3 (2.60 g, 9.13 mmol, 1.00 eq) in THF (13.0 mL) was added LDA (2 M, 15.5 mL, 3.40 eq) at −78° C., After 30 min, the mixture was warmed up to −25° C., and dry HCOH, obtained by thermal decomposition of paraformaldehyde (2.93 g, 91.3 mmol, 10.0 eq) was bubbled by the N₂ stream. The mixture was stirred at −25° C. for 3 hrs. TLC (Petroleum ether:Ethyl acetate=0:1, R_(f)=0.41) indicated compound 7-3 was consumed completely and two new spots formed. The reaction mixture was quenched by addition of 10% aq. HCl (3.00 mL) and then extracted with DCM (20 mL, 10 mL, 5 mL). The combined organic layers were washed with brine (10 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The residue was purified by column chromatography (SiO2, Petroleum ether/Ethyl acetate=10/1). Compound 7-4 (1.00 g, 3.18 mmol, 34.7% yield) was obtained as a yellow solid. ¹H NMR: 400 MHz CDCl₃. δ 7.30-7.61 (m, 8H), 4.41-4.45 (m, 1H), 4.21 (br s, 1H), 3.75 (dd, J=7.20, 5.20 Hz, 1H), 3.41 (s, 3H), 2.79-2.85 (m, 1H).

General Procedure for Preparation of Compound 7-5

To a solution of compound 7-4 (0.50 g, 1.59 mmol, 1.00 eq) in DCM (2.50 mL) was added TEA (321 mg, 3.18 mmol, 442 μL, 2.00 eq) and MsCl (236 mg, 2.07 mmol, 159 μL, 1.30 eq). The mixture was stirred at 0° C. for 4 hrs. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.43) indicated compound 7-4 was consumed completely and one new spot formed. The reaction mixture was quenched by addition H₂O (10.0 mL), and then extracted with DCM (10 mL, 8 mL, 5 mL). The combined organic layers were washed with brine (5 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The crude product compound 7-5 (0.80 g, crude) was used into the next step without further purification. ¹H NMR: 400 MHz CDCl₃. δ 7.56-7.61 (m, 2H), 7.39-7.56 (m, 4H), 7.32-7.36 (m, 2H), 5.09 (dd, J=10.0, 7.20 Hz, 1H), 4.84 (dd, J=10.0, 4.00 Hz, 1H), 3.98 (t, J=13.2 Hz, 1H), 3.42 (s, 3H), 3.15 (s, 3H).

General Procedure for Preparation of Target 8 (Compound 2)

To a solution of compound 7-5 (0.50 g, 1.27 mmol, 1.00 eq) in MeCN (2.50 mL) was added 2-(2-methoxyethoxy) ethanamine (151 mg, 1.27 mmol, 1.00 eq), K₂CO₃ (351 mg, 2.55 mmol, 2.00 eq). The mixture was stirred at 80° C. for 10 hrs. LC-MS showed compound 7-5 was consumed completely and one main peak with desired mass was detected. The reaction mixture was filtered and the filtrate was concentrated to give product. Phenomenex Luna C18 200*40 mm*10 um; mobile phase: [water (0.05% HCl)-ACN]; B %: 15%-45%, 10 min. Target 8 (Compound 2) (113 mg, 271 umol, 21.3% yield) was obtained as a yellow solid. ¹H NMR: 400 MHz MeOD δ 7.71-7.75 (m, 3H), 7.59-7.66 (m, 2H), 7.51-7.53 (m, 2H), 7.35 (d, J=2.40 Hz, 1H), 4.20 (t, J=5.20 Hz, 1H), 3.86 (t, J=4.80 Hz, 3H), 3.65-3.75 (m, 3H), 3.59-3.61 (m, 2H), 3.48 (s, 3H), 3.44 (br d, J=5.20 Hz, 2H), 3.36 (s, 3H). LC/MS: (M⁺H⁺)=416.2. HPLC: RT=2.226.

General Procedure for Preparation of Target 9 (Compound 3)

To a solution of compound 7-5 (0.20 g, 509 umol, 1.00 eq) in MeCN (1.00 mL) was added 2-methoxyethanamine (38.2 mg, 509 μmol, 44.2 μL, 1.00 eq), K-2CO (140 mg, 1.02 mmol, 2.00 eq). The mixture was stirred at 80° C. for 10 hr. LC-MS showed compound 7-5 was consumed completely and one main peak with desired mass was detected. The reaction mixture was filtered and the filtrate was concentrated to give product. The residue was purified by prep-HPLC (column: Welch Xtimate C18 250*50 mm*10 um; mobile phase: [water (10 mM NH₄HCO₃)-ACN]; B %: 35%-65%, 10 min). Target 9 (Compound 3) (62 mg, 149 μmol, 29.2/6 yield) was obtained as a yellow solid. ¹H NMR: 400 MHz CDCl₃. δ 7.60-7.63 (m, 2H), 7.48-7.56 (m, 2H), 7.45 (d, J=7.60 Hz, 2H), 7.29-7.31 (m, 2H), 3.86 (br t, J=6.00 Hz, 1H), 3.56 (br d, J=2.80 Hz, 4H), 3.42 (s, 3H), 3.40 (s, 3H), 2.97 (br s, 2H). LC/MS: (M⁺H⁺)=372.1. HPLC: RT=2.174.

Example 3. Synthesis of Compound 4 General Procedure for Preparation of Compound 10-2

With reference to FIG. 6, To a solution of compound 10-1 (5.00 g, 21.6 mmol, 1.00 eq) in DCM (35.0 mL) was added TEA (6.55 g, 64.8 mmol, 3.00 eq) at 0° C., and then a solution of compound 10-1A (8.71 g, 43.2 mmol, 2.00 eq) in DCM (15.0 mL) was added drop wise. The mixture was stirred at 25° C. for 16 h. TLC (Petroleum ether:Ethyl acetate=4:1, R_(f)=0.43) indicated compound 10-1 was consumed completely and three new spots formed. The reaction mixture was diluted with H₂O (200 mL) and extracted with EtOAc (150 mL). The combined organic layers were washed with brine (20.0 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give compound 10-2 (5.40 g, crude) as a light yellow solid which was used into next step without further purification.

General Procedure for Preparation of Compound 10-3

To a solution of compound 10-2 (5.40 g, 15.3 mmol, 1.00 eq) in NH₃/MeOH (7.00 M, 54.0 mL, 24.7 eq) was added 6,7,8,9-tetrazatricyclodecane (1.21 g, 8.67 mmol, 5.66 e⁻¹ eq). The mixture was stirred at 60° C. for 16 h. TLC (Dichloromethane:Methanol=10:1, R_(f)=0.59) indicated compound 10-2 was consumed completely and three new spots formed. The reaction mixture was under reduced pressure to give compound 10-3 (6.20 g, crude) as a yellow solid which was used into next step without further purification. ¹H NMR: 400 MHz CDCl₃. δ 9.11 (s, 1H), 7.54 (d, J=6.8 Hz, 2H), 7.41-7.48 (m, 4H), 7.31 (s, 1H), 7.14 (d, J=8.8 Hz, 1H), 4.38 (br s, 2H).

General Procedure for Preparation of Compound 10-4A

To a solution of compound 10-3 (2.00 g, 7.39 mmol, 1.00 eq) in DMSO (5.00 mL) was added t-BuOK (3.32 g, 29.6 mmol, 4.00 eq) and compound 10-3A (3.31 g, 14.8 mmol, 2.00 eq). The mixture was stirred at 50° C. for 6 h in a sealed tube. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.51) indicated compound 10-3 was consumed completely and one major new spot formed. The reaction mixture was quenched by addition saturated NH₄Cl (10.0 mL), and then extracted with EtOAc (10.0 mL, 5.00 mL). The combined organic layers were washed with brine (2.00 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The crude product was triturated with MTBE (5.00 mL) at 20° C. for 0.5 h. Compound 10-4A (1.20 g, 2.90 mmol, 39.2% yield) was obtained as a white solid. ¹H NMR: 400 MHz CDCl₃. δ 7.65 (d, J=7.2 Hz, 2H), 7.48-7.53 (m, 2H), 7.41-7.45 (m, 3H), 7.27-7.28 (m, 1H), 4.82 (d, J=10.4 Hz, 1H), 4.51 (m, 1H), 4.22-4.27 (m, 1H), 3.97-4.04 (m, 1H), 3.78 (d, J=10.4 Hz, 1H), 3.18-3.34 (m, 2H), 1.34 (s, 9H).

General Procedure for Preparation of Compound 10-6A

A mixture of compound 10-4A (1.20 g, 2.90 mmol, 1.00 eq) in HCI/EtOAc (8.00 mL) was stirred at 20° C. for 0.5 h under N₂ atmosphere. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.00) indicated compound 10-4A was consumed completely and one new spot formed. LC-MS showed compound 10-4A was consumed completely and one main peak with desired mass was detected. The reaction mixture was concentrated under reduced pressure to remove MeOH to give compound 10-6A (1.00 g, crude, HCl) as a yellow solid which was used into next step without further purification. ¹H NMR: 400 MHz MeOD. δ 8.02-8.05 (m, 1H), 7.91-7.95 (m, 1H), 7.83-7.87 (m, 3H), 7.73-7.76 (m, 2H), 7.46 (d, J=2.4 Hz, 1H), 4.67 (d, J=13.2 Hz, 1H), 4.40 (d, J=13.6 Hz, 1H), 4.27-4.378 (m, 2H), 3.35-3.51 (m, 2H).

General Procedure for Preparation of Target 10 (Compound 4)

A mixture of compound 10-6A (0.30 g, 857 μmol, 1.00 eq, HCl) and Amberlyst|r A-21, ion exchange resin (0.30 g) in MeOH (6.00 mL) was stirred at 20° C. for 0.5 h, then the mixture was filtered and concentrated under reduced pressure to give a residue. The residue was added to a suspension of compound 50586-80-6 (258 mg, 942 μmol, 1.10 eq) and K₂CO₃ (237 mg, 1.71 mmol, 2.00 eq) in CH₃CN (3.00 mL), the resulting mixture was stirred at 90° C. for 15 h. LC-MS showed ˜60% of compound 10-6A remained. Several new peaks were shown on LC-MS and −30% of desired compound was detected. The reaction mixture filtered and concentrated under reduced pressure to give a residue. The residue was purified by prep-HPLC (neutral condition:column: Waters X bridge Prep OBD C18 150*40 mm*10 um; mobile phase: [water (10 mM NH₄HCO₃)-ACN]; B %: 25%-50%, 8 min) to give Target 10 (Compound 4) (0.095 g, 228 μmol, 26.7% yield, 100% purity) as a yellow oil. ¹H NMR: 400 MHz CDCl₃. δ 7.61 (d, J=7.2 Hz, 2H), 7.40-7.51 (m, 5H), 7.27 (m, 1H), 4.80 (d, J=10.8 Hz, 1H), 4.33-4.40 (m, 1H), 3.68-3.79 (m, 2H), 3.47 (s, 4H), 3.38 (t, J=4.8 Hz, 2H), 3.35 (s, 3H), 2.78 (t, J=6.8 Hz, 2H), 2.60-2.71 (m, 2H), 1.26 (s, 1H). LC/MS: (M+1): 416.0. HPLC: RT=2.439.

Example 4. Synthesis of Compound 5 General Procedure for Preparation of Compound 11-1

With reference to FIG. 7, A solution of compound 10-3A (333 mg, 1.99 mmol, 1.20 eq) in DMF (1.00 mL) was added dropwise to a suspension of compound 10-3 (0.45 g, 1.66 mmol, 1.00 eq) and NaH (73.1 mg, 1.83 mmol, 60% purity, 1.10 eq) in DMF (4.00 mL) at 0° C. The mixture was stirred at 25° C. for 16 h. TLC (Petroleum ether:Ethyl acetate=1:1, R_(f)=0.61) indicated compound 10-3 was consumed completely, and one major new spot with lower polarity was detected. The reaction mixture was quenched by addition NH₄Cl (15.0 mL) at 20° C., and then diluted with H₂O (50.0 mL) and extracted with EtOAc (15.0 mL, 10.0 mL, 5.00 mL). The combined organic layers were washed with brine (5.00 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The residue was purified by column chromatography (SiO₂, Petroleum ether/Ethyl acetate=30/1 to 5/1) to give compound 11-1 (0.55 g, 1.54 mmol, 92.7% yield) as a yellow solid. ¹H NMR: 400 MHz CDCl₃. δ 7.63 (d, J=7.2 Hz, 2H), 7.50-7.62 (m, 2H), 7.43-7.49 (m, 2H), 7.29-7.31 (m, 2H), 4.86 (d, J=10.2 Hz, 1H), 4.58 (d, J=17.6 Hz, 1H), 4.45 (d, J=17.2 Hz, 1H), 4.23 (d, J=1.6 Hz, 2H), 4.17-4.23 (m, 2H), 3.88 (d, J=10.8 Hz, 1H), 1.21-1.25 (m, 1H).

General Procedure for Preparation of Compound 11-2

A mixture of compound 11-1 (0.55 g, 1.54 mmol, 1.00 eq), LiOH.H₂O (97.0 mg, 2.31 mmol, 1.50 eq), and H₂O (2.00 mL) in MeOH (2.00 mL) was degassed and purged with N₂ for 3 times, and then the mixture was stirred at 20° C. for 2 hrs under N₂ atmosphere. TLC (Petroleum ether:Ethyl acetate=1:1,R_(f)=0.00) indicated compound 11-1 was consumed completely and one new spot formed. The reaction mixture was quenched by addition HCl (5.00 mL, 1.00 M) at 20° C., and extracted with EtOAc (10.0 mL). The combined organic layers were washed with brine (3.00 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give compound 11-2 (0.50 g, 1.52 mmol, 98.6% yield) as a yellow solid which was used into next step without further purification. ¹H NMR: 400 MHz CDCl₃. δ 7.52 (d, J=7.2 Hz, 2H), 7.43-7.50 (m, 2H), 7.34-7.43 (m, 2H), 7.19-7.22 (m, 2H), 4.80 (d, J=10.8 Hz, 1H), 4.55 (d, J=7.2 Hz, 1H), 4.53 (d, J=8.0 Hz, 1H), 3.79 (d, J=11.2 Hz, 1H).

General Procedure for Preparation of Target 11 (Compound 5)

To a solution of compound 11-2 (0.45 g, 1.37 mmol, 1.00 eq) in DCM (3.00 mL) was added DIEA (265 mg, 2.05 mmol, 1.50 eq), and then HATU (573 mg, 1.51 mmol, 1.10 eq), compound 11-2A (179 mg, 1.51 mmol, 1.10 eq) was added at 0° C. The mixture was stirred at 20° C. for 16 hrs. LC-MS showed compound 11-2 was consumed completely and one main peak with desired mass was detected. The reaction mixture was diluted with H₂O (5.00 mL) and extracted with EtOAc (2.00 mL×3). The combined organic layers were washed with brine (2.00 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The residue was purified by prep-HPLC (column: Welch Xtimate C18 15025 mm*5 μm; mobile phase: [water (10 mM NH₄HCO₃)-ACN]; B %: 20%-50%, 10 min) to give Target 11 (Compound 5) (160 mg, 372 μmol, 27.2% yield) as white solid. ¹H NMR: 400 MHz CDCl₃. δ 7.61-7.66 (m, 3H), 7.50-7.60 (m, 2H), 7.43-7.45 (m, 2H), 7.28 (d, J=2.4 Hz, 1H), 6.61 (t, J=5.2 Hz, 1H), 4.86 (d, J=10.8 Hz, 1H), 4.60 (d, J=15.6 Hz, 1H), 4.57 (d, J=15.6 Hz, 1H), 4.17 (d, J=15.6 Hz, 1H), 3.87 (d, J=10.8 Hz, 1H), 3.49-3.58 (m, 8H), 3.38 (s, 3H). LC/MS: (M+1): 430.1. HPLC: RT=2.381.

Example 5. Synthesis of Compound 6

With reference to FIG. 8, a mixture of compound 10-6A (0.10 g, 286 μmol, 1.00 eq, HCl) and Amberlyst|r A-21, ion exchange resin (0.10 g) in MeOH (2.00 mL) was stirred at 20° C. for 0.5 h, then the mixture was filtered and concentrated under reduced pressure to give a residue. The residue was added to a suspension of compound 50586-80-6 (235 mg, 857 umol, 3.00 eq) and K₂CO₃ (78.9 mg, 571 μmol, 2.00 eq) in CH₃CN (1.00 mL), the resulting mixture was stirred at 90° C. for 15 h. LC-MS showed ˜50% of compound 10-6A remained. Several new peaks were shown on LC-MS and ˜20% of desired compound was detected. The reaction mixture was filtered and concentrated under reduced pressure to give a residue. The residue was purified by prep-TLC (SiO₂, DCM:MeOH=10:1) to give Compound 6 (0.017 g, 31.5 μmol, 11.0% yield, 96.0% purity) as a yellow oil. ¹H NMR: 400 MHz CDCl₃. δ 7.60-7.62 (m, 2H), 7.54-7.57 (m, 1H), 7.46-7.51 (m, 2H), 7.40-7.44 (m, 2H), 7.26-7.27 (m, 1H), 4.80 (d, J=10.8 Hz, 1H), 4.18-4.25 (m, 1H), 3.72-3.77 (m, 2H), 3.33-3.49 (m, 18H), 2.75 (t, J=6.4 Hz, 2H), 2.61-2.70 (m, 4H). LC/MS: (½M+1, M+1): 259.6, 518.2. HPLC: RT=2.524.

OTHER EMBODIMENTS

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the invention that come within known or customary practice within the art to which the invention pertains and may be applied to the essential provides hereinbefore set forth, and follows in the scope of the claims. 

1. A compound having the structure of Formula (I):

or a pharmaceutically acceptable salt thereof, wherein: R^(A) is R^(E), hydrogen, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —OR^(D1), —N(R^(D1a))₂, or —SR^(D1), wherein R^(D1) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom; R^(B) is R^(E), hydrogen, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphaticl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group; each instance of R^(C) and R^(D) is, independently, R^(E), hydrogen, halogen, nitro, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —OR^(D1a), —N(R^(D1a))₂, or —SR^(D1a), wherein R^(D1a) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom; X is O, NR^(F), or CHR^(F); p is 1, 2, 3, or 4; n is 1, 2, 3, 4, or 5; R^(E) is a moiety that restricts the compound of Formula (I) to the peripheral nervous system, provided that the compound of Formula (I) comprises at least one R^(E); and R^(F) is a nitrogen radical that combines with R^(B) to form a fused 5-membered heterocyclyl or heteroaryl ring.
 2. The compound of claim 1, wherein R^(E) is optionally substituted C₁₋₅₀ heteroaliphatic, —OR^(E1), —N(R^(E1))₂, —NO₂, —CN, —SR^(E1), —CH₂OR^(E1), —CH₂N(R^(E1))₂, —CH₂SR^(E1), —NR^(E1)C(═O)R^(E1), —C(═O)N(R^(E1))₂, —SC(═O)R^(E1), —C(═O)SR^(E1), —OC(═O)R^(E1), —C(═O)OR^(E1), —NR^(E)C(═S)R^(E1), —C(═S)NR^(E1), trans-CR^(E1)═CR^(E1), cis-R^(E1)═CR^(E1), —C≡C—R^(E1), —S(═O)R^(E1), —S(═O)OR^(E1), —OS(═O)R^(E1), —S(═O)N(R^(E1))₂, —NR^(E1)S(═O)R^(E1), —S(═O)₂R^(E1), —S(═O)₂OR^(E1), —OS(═O)₂R^(E1), —S(═O)₂N(R^(E1))₂R^(E1), or is of the formula:

R^(E1) is independently selected from hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom; or a pharmaceutically acceptable salt thereof.
 3. The compound of claim 1, having the structure of Formula (II):

or a pharmaceutically acceptable salt thereof.
 4. The compound of claim 1, having the structure of Formula (III):

or a pharmaceutically acceptable salt thereof.
 5. The compound of claim 1, having the structure of Formula (IV):

or a pharmaceutically acceptable salt thereof.
 6. The compound of claim 1, having the structure of Formula (V):

or a pharmaceutically acceptable salt thereof.
 7. The compound of claim 3, having the structure of Formula (IIa):

or a pharmaceutically acceptable salt thereof.
 8. The compound of claim 3, having the structure of Formula (IIb):

or a pharmaceutically acceptable salt thereof.
 9. The compound of claim 3, having the structure of Formula (IIc):

or a pharmaceutically acceptable salt thereof.
 10. The compound of claim 3, having the structure of Formula (IId):

or a pharmaceutically acceptable salt thereof.
 11. The compound of claim 1, having the structure of Formula (VI):

or a pharmaceutically acceptable salt thereof.
 12. The compound of claim 1, having the structure of Formula (VII):

or a pharmaceutically acceptable salt thereof.
 13. The compound of any one of claims 1, 3, 5-8, or 10, wherein R^(B) is optionally substituted alkyl.
 14. The compound of claim 13, wherein R^(B) is methyl.
 15. The compound of claim 14, wherein the compound has the structure of:

or a pharmaceutically acceptable salt thereof.
 16. The compound of claim 4, having the structure of Formula (IIIa):

or a pharmaceutically acceptable salt thereof.
 17. The compound of claim 4, having the structure of Formula (IIIb):

or a pharmaceutically acceptable salt thereof.
 18. The compound of claim 4, having the structure of Formula (IIIc):

or a pharmaceutically acceptable salt thereof.
 19. The compound of claim 4, having the structure of Formula (IIId):

or a pharmaceutically acceptable salt thereof.
 20. The compound of any one of claims 1, 4-6, or 17-19, wherein R^(A) is H.
 21. The compound of claim 20, wherein the compound has the structure of:

or a pharmaceutically acceptable salt thereof.
 22. The compound of any one of claims 1-21, wherein R^(E) is optionally substituted C₁₋₅₀ heteroalkyl, —OR^(E1), —N(R^(E1))₂, —NO₂, —ON, —SR^(E1), —CH₂OR^(E1), —CH₂N(R^(E1))₂, —CH₂SR^(E1), —NR^(E1)C(═O)R^(E1), —C(═O)N(R^(E1))₂, —SC(═O)R^(E1), —C(═O)SR^(E1), —OC(═O)R^(E1), —C(═O)OR^(E1), —NR^(E)C(═S)R^(E1), —C(═S)NR^(E1), trans-CR^(E1)═CR^(E1), cis-CR^(E1)═CR^(E1), —OCCR^(E1), —S(═O)R^(E1), —S(═O)OR^(E1), —OS(═O)R^(E1), —S(═O)N(R^(E1))₂, —NR^(E1)S(═O)R^(E1), —S(═O)₂R^(E1), —S(═O)₂OR^(E1), —OS(═O)₂R^(E1), —S(═O)₂N(R^(E1))₂R^(E1); wherein R^(E1) is independently hydrogen, optionally substituted acyl, optionally substituted aliphatic, optionally substituted heteroaliphatic, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to an nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom.
 23. The compound of any one of claims 1-21, wherein R^(E) is of the formula:


24. The compound of any one of claims 1-22, wherein R^(E) is C₁₋₁₀ heteroalkyl.
 25. The compound of claim 24, wherein R^(E) is of the formula:

or a pharmaceutically acceptable salt thereof.
 26. A pharmaceutical composition comprising the compound or pharmaceutically acceptable salt according to any one of claims 1-25 and a pharmaceutically acceptable excipient.
 27. A method of reducing tactile dysfunction in a human subject diagnosed with Autism Spectrum Disorder (ASD), Rett Syndrome (RTT), Phelan McDermid syndrome (PMS), or Fragile X Syndrome, by administering to the subject the compound or pharmaceutically acceptable salt of any one of claims 1-25, or the pharmaceutical composition of claim 26 in an amount and for a duration sufficient to reduce the tactile dysfunction.
 28. A method of reducing anxiety or social impairment in a human subject diagnosed with ASD, RTT, PMS, or Fragile X Syndrome by administering to the subject the compound or pharmaceutically acceptable salt of any one of claims 1-25, or the pharmaceutical composition of claim 26 in an amount and for a duration sufficient to reduce the anxiety or social impairment. 